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CARNEGIE INSTITUTION 
OF WASHINGTON 



YEAR BOOK No. 52 
July 1, 1952— June 30, 1953 

With Administrative Reports through December 11, 1953 



erf ^ 




CARNEGIE INSTITUTION OF WASHINGTON 
WASHINGTON, D. C. 

1953 



THE LORD BALTIMORE PRESS, BALTIMORE, MARYLAND 



CONTENTS 

PAGE 

Officers and Staff 1953 v 

Organization, Plan, and Scope xi 

Articles of Incorporation xii 

By-Laws of the Institution xv 

Abstract of Minutes of the Fifty-Fifth Meeting of the Board of Trustees .... xxi 

Report of the Executive Committee xxiii 

Report of Auditors xxv 

Report of the President 1-18 

Reports of Departmental Activities and Co-operative Studies 

Astronomy 

Mount Wilson and Palomar Observatories 3 

Terrestrial Sciences 

Geophysical Laboratory 39 

Department of Terrestrial Magnetism 97 

Biological Sciences 

Department of Plant Biology 145 

Department of Embryology 183 

Department of Genetics 205 

Archaeology 

Department of Archaeology 249 

Reports of Research Associates 

E. A. Lowe 297 

Bibliography 299 

Index 301 



111 



PRESIDENT AND TRUSTEES 



James F. Bell 
Robert Woods Bliss 
Lindsay Bradford 
Omar N. Bradley 
W. Cameron Forbes 
Walter S. Gifford 
Crawford H. Greenewalt 
Caryl P. Haskins 



Robert Woods Bliss 
Vannevar Bush 



Alfred L. Loomis 



Barklie Henry 



Robert A. Lovett 



Crawford H. Greenewalt 



Barklie Henry 



Alfred L. Loomis 



James F. Bell 



PRESIDENT 
Vannevar Bush 

BOARD OF TRUSTEES 

Elihu Root, Jr., Chairman 

Lindsay Bradford, Vice-Chairman 

Robert Woods Bliss, Secretary * 

Barklie Henry 
Ernest O. Lawrence 
Alfred L. Loomis 
Robert A. Lovett 
Keith S. McHugh 
Roswell Miller 
Henry S. Morgan 
Seeley G. Mudd 

Executive Committee 

Elihu Root, Jr., Chairman 
Caryl P. Haskins 
Barklie Henry 
Henry S. Morgan 

Finance Committee 

Lindsay Bradford, Chairman 
Henry S. Morgan 
Henning W. Prentis, Jr. 

Auditing Committee 
Roswell Miller, Chairman 

Nominating Committee 

Henry S. Morgan, Chairman 
Keith S. McHugh 

Committee on Astronomy 

Seeley G. Mudd, Chairman 
Roswell Miller 

Committee on Terrestrial Sciences 
Ernest O. Lawrence, Chairman 

Committee on Biological Sciences 

Caryl P. Haskins, Chairman 
William I. Myers 

Committee on Archaeology 

Henry R. Shepley, Chairman 
Robert Woods Bliss 



William I. Myers 
Henning W. Prentis, Jr. 
David Rockefeller 
Elihu Root, Jr. 
Henry R. Shepley 
Charles P. Taft 
Juan T. Trippe 
Robert E. Wilson 



Henning W. Prentis, Jr. 
Henry R. Shepley 



Elihu Root, Jr. 



Keith S. McHugh 



Elihu Root, Jr. 



Elihu Root, Jr. 



David Rockefeller 



Charles P. Taft 



Juan T. Trippe 



* Secretary of Board of Trustees March 26 — December 11, 1953, Henry S. Morgan. 

V 



FORMER PRESIDENTS AND TRUSTEES 

PRESIDENTS 

Daniel Coit Gilman, 1902-1904 Robert Simpson Woodward, 1904-1920 

John Campbell Merriam, President 1 921-1938; President Emeritus 1 939-1945 

TRUSTEES 



Alexander Agassiz 
George J. Baldwin 
Thomas Barbour 
John S. Billings 
Robert S. Brookings 
John L. Cadwalader 
William W. Campbell 
John J. Carty 
Whitefoord R. Cole 
Frederic A. Delano 
Cleveland H. Dodge 
William E. Dodge 
Charles P. Fenner 
Homer L. Ferguson 
Simon Flexner 
James Forrestal 
William N. Frew 
Lyman J. Gage 
Cass Gilbert 
Frederick H. Gillett 
Daniel C. Gilman 
John Hay 
Myron T. Herrick 
Abram S. Hewitt 
Henry L. Higginson 
Ethan A. Hitchcock 
Henry Hitchcock 
Herbert Hoover 
William Wirt FIowe 
Charles L. Hutchinson 
Walter A. Jessup 
Frank B. Jewett 
Samuel P. Langley 
Charles A. Lindbergh 
William Lindsay 
Henry Cabot Lodge 



1904-05 
1925-27 
1934-46 
1902-13 
1910-29 
1903-14 
1929-38 
1916-32 

J 9 2 5-34 
1927-49 

1903-23 

1902-03 

1914-24 

1927-52 

1910-14 

1948-49 

1902-15 

1902-12 

1924-34 

I 9 2 4"35 
1902-08 

1902-05 

1915-29 

1902-03 

1902-19 

1902-09 

1902-02 

1920-49 

1903-09 

1902-04 

1938-44 

!933-49 
1904-06 

T 934"39 
1902-09 

1914-24 



Seth Low 
Wayne MacVeagh 
Andrew W. Mellon 
Darius O. Mills 
S. Weir Mitchell 
Andrew J. Montague 
William W. Morrow 
William Church Osborn 
James Parmelee 
Wm. Barclay Parsons 
Stewart Paton 
George W. Pepper 
John J. Pershing 
Henry S. Pritchett 
Gordon S. Rentschler 
Elihu Root 
Julius Rosenwald 
Martin A. Ryerson 
Theobald Smith 
John C. Spooner 
William Benson Storey 
Richard P. Strong 
William H. Taft 
William S. Thayer 
James W. Wadsworth 
Charles D. Walcott 
Frederic C. Walcott 
Henry P. Walcott 
Lewis H. Weed 
William H. Welch 
Andrew D. White 
Edward D. White 
Henry White 
George W. Wickersham 
Robert S. Woodward 
Carroll D. Wright 



1902-16 
1902-07 
1924-37 
1902-09 
1902-14 

1902-29 
1927-34 
1917-31 
1907-32 
1916-42 
1914-19 

I 93°~43 
1906-36 

1946-48 

1902-37 

1929-31 

1908-28 

1914-34 

1902-07 

1924-39 

1934-48 

1906-15 

1929-32 

1932-52 

1902-27 

1931-48 

1910-24 

J935-5 2 
1906-34 

1902-03 

1902-03 

1913-27 

1909-36 

1905-24 

1902-08 



Besides the names enumerated above, the following were ex-officio members of the Board 
of Trustees under the original charter, from the date of organization until April 28, 1904: 
the President of the United States, the President of the Senate, the Speaker of the House 
of Representatives, the Secretary of the Smithsonian Institution, the President of the 
National Academy of Sciences. 



VI 



STAFF OF INVESTIGATORS FOR THE YEAR 1953 



ASTRONOMY 

Mount Wilson and Palomar Observatories 

813 Santa Barbara Street, Pasadena 4, California 

Mount Wilson Observatory organized in 1904; George E. Hale, Director 1 904-1 923, Honorary Director 
1923-1936; Walter S. Adams, Director 1924-1945. Unified operation with the Palomar Observatory of 
the California Institute of Technology began in 1948. 



Ira S. Bowen, Director 
Walter Baade 
Horace W. Babcock 
William A. Baum 
Armin J. Deutsch 
Jesse L. Greenstein 
|Edwin P. Hubble 
Milton L. Humason 
Rudolph L. Minkowski 



Guido Munch 
Seth B. Nicholson 
Donald E. Osterbrock 
Edison Pettit 
Robert S. Richardson 
Allan R. Sandage 
# Albert G. Wilson 
Olin C. Wilson 
Fritz Zwicky 



TERRESTRIAL SCIENCES 

Geophysical Laboratory 

2801 Upton Street, N.W., Washington 8, D. C. 

Organized in 1906, opened in 1907; Arthur L. Day, Director 1909-1936; Leason H. Adams, Acting 
Director 1 936-1 937, Director 1938 — August 1, 1952; George W. Morey, Acting Director August 1, 1952 — 
August 31, 1953. 



Philip H. Abelson, Director 

Francis R. Boyd, Jr. 

Felix Chayes 

Gordon L. Davis 

Joseph L. England 

Hans P. Eugster 

Joseph W. Greig 

Department of Terrestrial Magnetism 



Frank C. Kracek 
William S. MacKenzie 
George W. Morey 
J. Frank Schairer 
# 0. Frank Tuttle 
Hatten S. Yoder, Jr. 



5241 Broad Branch Road, N.W., Washington 15, D. C. 

Organized in 1904; Louis A. Bauer, Director 1 904-1 929; John A. Fleming, Acting Director 1 929-1 934, 
Director 1 935-1 946. 



Merle A. Tuve, Director 
JPhilip H. Abelson 

L. Thomas Aldrich 

Ellis T. Bolton 

Roy J. Britten 

Bernard F. Burke 

Dean B. Cowie 

John W. Firor 

Scott E. Forbush 

John W. Graham 

Norman P. Heydenburg 
§Ellis A. Johnson 

Richard B. Roberts 

Howard E. Tatel 

Georges M. Temmer 

George R. Tilton 

Ernest H. Vestine 

Harry W. Wells 

George W. Wetherill 



Visiting Investigators 
William R. Duryee 
||George B. Field 
Paul W. Gast 
Pembroke J. Hart 
H. Lawrence Helfer 
B. Y. Mills 
Leif Owren 
Irena Z. Roberts 
F. Graham Smith 
M. Sugiura 



* Resigned in 1953. 

t Deceased in 1953. 

tTo August 31, 1953. 

§ On leave of absence. 

|| Term of appointment completed in 1953. 



Vll 



CARNEGIE INSTITUTION OF WASHINGTON 

BIOLOGICAL SCIENCES 
Department of Plant Biology 

Stanford, California 

Desert Laboratory, opened in 1903, became headquarters of Department of Botanical Research in 1905; 
name changed to Laboratory for Plant Physiology in 1923; Daniel T. MacDougal, Director 1906-1927. 
Reorganized in 1928 as Division of Plant Biology, including Ecology; Herman A. Spoehr, Chairman 
1 927-1 930 and 1 931-1947, Chairman Emeritus 1 947-1 950. Name changed to Department of Plant 
Biology in 1951. 

C. Stacy French, Director Guest Investigators 
Jens C. Clausen Robert Hill 

Paul Grun Hiroshi Tamiya 

William M. Hiesey Hemming I. Virgin 

Harold W. Milner 

Malcolm A. Nobs Visiting Investigators 
James H. C. Smith Elias Landolt 

Violet K. Young Jack E. Myers 



Department of Embryology 

Wolfe and Madison Streets, Baltimore 5, Maryland 
Organized in 191 4; Franklin P. Mall, Director 191 4-19 17; George L. Streeter, Director 191 8-1940 

*George W. Corner, Director Consultant 

George W. Bartelmez 



Samuel R. M. Reynolds, Acting Director 
David W. Bishop 
Bent G. Boving 
Robert K. Burns 
Arpad Csapo 



Research Associate 
Elizabeth M. Ramsey 



Department of Genetics 

Cold Spring Harbor, hong Island, New Yor\ 

Station for Experimental Evolution opened in 1904; name changed to Department of Experimental 
Evolution in 1906; combined with Eugenics Record Office in 1921 to form Department of Genetics. 
Charles B. Davenport, Director 1904-1934; Albert F. Blakeslee, Director 1935-1941. 



Milislav Demerec, Director 
Alfred D. Hershey 
Berwind P. Kaufmann 
Barbara McClintock 
Margaret R. McDonald 
JN. Visconti 

§EVELYN M. WlTKIN 

* On leave of absence to September 1, 1953. 

t Resigned in 1953. 

§ On leave of absence. 

|| Term of appointment completed in 1953. 



Special Investigators 
Maurice H. Bernstein 

||A. M. M. Berrie 

1 1 Irving Galinsky 
Alan Garen 
Jean Hemmerly 
June Dixon Hudis 

||Edgar L. Labrum 
Dan L. Lindsley 
Hermann Moser 
Neville Symonds 

||r. c. von borstel 



Vlll 



STAFF OF INVESTIGATORS FOR THE YEAR 1953 

ARCHAEOLOGY 

Department of Archaeology 

io Frisbie Place, Cambridge 38, Massachusetts 

Department of Historical Research organized in 1903; Andrew C. McLaughlin, Director 1 903-1 905; 
J. Franklin Jameson, Director 1 905-1 928. In 1930 this Department was incorporated as a section of 
United States history in a new Division of Historical Research; Alfred V. Kidder, Chairman 1 930-1 950. 
Name changed to Department of Archaeology in 1951. 

Harry E. D. Pollock, Director Edwin M. Shook 

Margaret W. Harrison, Editor A. Ledyard Smith 

Earl H. Morris Robert E. Smith 

Tatiana Proskouriakoff Gustav Stromsvik 

Karl Ruppert J. Eric S. Thompson 
Anna O. Shepard 



RESEARCH ASSOCIATES 

Research Associates Engaged in Post-Retirement Studies 
Chester H. Heuser, Embryology Ralph L. Roys, History 

Research Associates Connected with Other Institutions 

Ralph W. Chaney (University of California), Paleobotany 
Louis B. Flexner (University of Pennsylvania), Embryology 
Arthur T. Hertig (Boston Lying-in Hospital), Embryology 
E. A. Lowe (The Institute for Advanced Study), Paleography 



IX 



OFFICE OF ADMINISTRATION 

Vannevar Bush, President 

Paul A. Scherer, Executive Officer 

Samuel Callaway, Assistant to the President 

Ailene J. Bauer, Director of Publications 

Dorothy R. Swift, Editor 

John A. Fleming, Adviser in International Scientific Relations 

Earle B. Biesecker, Bursar 

J. Stanley Lingebach, Assistant Bursar 

James F. Sullivan, Assistant to the Bursar 

Richard F. F. Nichols, Executive Assistant to the Finance Committee 



ORGANIZATION, PLAN, AND SCOPE 

The Carnegie Institution of Washington was founded by Andrew Carnegie, 
January 28, 1902, when he gave to a board of trustees an endowment of registered 
bonds of the par value of ten million dollars. To this fund an addition of two 
million dollars was made by Mr. Carnegie on December 10, 1907, and a further 
addition of ten million dollars was made by him on January 19, 191 1. Further- 
more, the income of a reserve fund of about three million dollars, accumulated 
in accordance with the founder's specifications in 191 1, is now available for general 
use, and in recent years a total of ten million dollars has been paid by the Carnegie 
Corporation of New York as increase to the Endowment Fund of the Institution. 
The Institution was originally organized under the laws of the District of Columbia 
and incorporated as the Carnegie Institution, articles of incorporation having been 
executed on January 4, 1902. The Institution was reincorporated, however, by an 
act of the Congress of the United States, approved April 28, 1904, under the title 
o£ Carnegie Institution of Washington. (See existing Articles of Incorporation on 
following pages.) 

Organization under the new Articles of Incorporation was effected May 18, 1904, 
and the Institution was placed under the control of a board of twenty-four trustees, 
all of whom had been members of the original corporation. The trustees meet 
annually in December to consider the affairs of the Institution in general, the progress 
of work already undertaken, and the initiation of new projects, and to make 
the necessary appropriations for the ensuing year. During the intervals between 
the meetings of the trustees the affairs of the Institution are conducted by an 
Executive Committee chosen by and from the Board of Trustees and acting through 
the President of the Institution as chief executive officer. 

The Articles of Incorporation of the Institution declare in general "that the 
objects of the corporation shall be to encourage, in the broadest and most liberal 
manner, investigation, research, and discovery, and the application of knowledge 
to the improvement of mankind." 

The Institution is essentially an operating organization. It attempts to advance 
fundamental research in fields not normally covered by the activities of other agencies, 
and to concentrate its attention upon specific problems, with the idea of shifting 
attack from time to time to meet the more pressing needs of research as they develop 
with increase of knowledge. Some of these problems require the collaboration of 
several investigators, special equipment, and continuous effort. Many close relations 
exist among activities of the Institution, and a type of organization representing 
investigations in astronomy, in terrestrial sciences, in biological sciences, and in 
archaeology has been effected. Conference groups on various subjects have played 
a part in bringing new vision and new methods to bear upon many problems. 
Constant efforts are made to facilitate interpretation and application of results of 
research activities of the Institution. 



XI 



ARTICLES OF INCORPORATION 

Public No. 260. An Act to incorporate the Carnegie Institution of Washington. 

Be it enacted by the Senate and House of Representatives of the United States of 
America in Congress assembled, That the persons following, being persons who are 
now trustees of the Carnegie Institution, namely, Alexander Agassiz, John S. Billings, 
John L. Cadwalader, Cleveland H. Dodge, William N. Frew, Lyman J. Gage, 
Daniel C. Gilman, John Hay, Henry L. Higginson, William Wirt Howe, Charles L. 
Hutchinson, Samuel P. Langley, William Lindsay, Seth Low, Wayne MacVeagh, 
Darius O. Mills, S. Weir Mitchell, William W. Morrow, Ethan A. Hitchcock, 
Elihu Root, John C. Spooner, Andrew D. White, Charles D. Walcott, Carroll D. 
Wright, their associates and successors, duly chosen, are hereby incorporated and 
declared to be a body corporate by the name of the Carnegie Institution of Wash- 
ington and by that name shall be known and have perpetual succession, with the 
powers, limitations, and restrictions herein contained. 

Sec. 2. That the objects of the corporation shall be to encourage, in the broadest 
and most liberal manner, investigation, research, and discovery, and the application 
of knowledge to the improvement of mankind; and in particular — 

(a) To conduct, endow, and assist investigation in any department of science, 
literature, or art, and to this end to cooperate with governments, universities, colleges, 
technical schools, learned societies, and individuals. 

(b) To appoint committees of experts to direct special lines of research. 

(c) To publish and distribute documents. 

(d) To conduct lectures, hold meetings, and acquire and maintain a library. 

(e) To purchase such property, real or personal, and construct such building or 
buildings as may be necessary to carry on the work of the corporation. 

(f) In general, to do and perform all things necessary to promote the objects 
of the institution, with full power, however, to the trustees hereinafter appointed 
and their successors from time to time to modify the conditions and regulations 
under which the work shall be carried on, so as to secure the application of the 
funds in the manner best adapted to the conditions of the time, provided that the 
objects of the corporation shall at all times be among the foregoing or kindred thereto. 

Sec. 3. That the direction and management of the affairs of the corporation and 
the control and disposal of its property and funds shall be vested in a board of trustees, 
twenty-two in number, to be composed of the following individuals: Alexander 
Agassiz, John S. Billings, John L. Cadwalader, Cleveland H. Dodge, William N. 
Frew, Lyman J. Gage, Daniel C. Gilman, John Hay, Henry L. Higginson, William 
Wirt Howe, Charles L. Hutchinson, Samuel P. Langley, William Lindsay, Seth 
Low, Wayne MacVeagh, Darius O. Mills, S. Weir Mitchell, William W. Morrow, 
Ethan A. Hitchcoc\, Elihu Root, John C. Spooner, Andrew D. White, Charles D. 
Walcott, Carroll D. Wright, who shall constitute the first board of trustees. The 
board of trustees shall have power from time to time to increase its membership 
to not more than twenty-seven members. Vacancies occasioned by death, resignation, 
or otherwise shall be filled by the remaining trustees in such manner as the by-laws 

xii 



ARTICLES OF INCORPORATION 

shall prescribe; and the persons so elected shall thereupon become trustees and 
also members of the said corporation. The principal place of business of the said 
corporation shall be the city of Washington, in the District of Columbia. 

Sec. 4. That such board of trustees shall be entitled to take, hold, and administer 
the securities, funds, and property so transferred by said Andrew Carnegie to the 
trustees of the Carnegie Institution and such other funds or property as may at any 
time be given, devised, or bequeathed to them, or to such corporation, for the purposes 
of the trust; and with full power from time to time to adopt a common seal, to 
appoint such officers, members of the board of trustees or otherwise, and such 
employees as may be deemed necessary in carrying on the business of the corporation, 
at such salaries or with such remuneration as they may deem proper; and with 
full power to adopt by-laws from time to time and such rules or regulations as 
may be necessary to secure the safe and convenient transaction of the business of 
the corporation; and with full power and discretion to deal with and expend the 
income of the corporation in such manner as in their judgment will best promote 
the objects herein set forth and in general to have and use all powers and authority 
necessary to promote such objects and carry out the purposes of the donor. The 
said trustees shall have further power from time to time to hold as investments 
the securities hereinabove referred to so transferred by Andrew Carnegie, and any 
property which has been or may be transferred to them or such corporation by 
Andrew Carnegie or by any other person, persons, or corporation, and to invest 
any sums or amounts from time to time in such securities and such form and 
manner as are permitted to trustees or to charitable or literary corporations for 
investment, according to the laws of the States of New York, Pennsylvania, or 
Massachusetts, or in such securities as are authorized for investment by the said deed 
of trust so executed by Andrew Carnegie, or by any deed of gift or last will and 
testament to be hereafter made or executed. 

Sec. 5. That the said corporation may take and hold any additional donations, 
grants, devises, or bequests which may be made in further support of the purposes 
of the said corporation, and may include in the expenses thereof the personal expenses 
which the trustees may incur in attending meetings or otherwise in carrying out 
the business of the trust, but the services of the trustees as such shall be gratuitous. 

Sec. 6. That as soon as may be possible after the passage of this Act a meeting 
of the trustees hereinbefore named shall be called by Daniel C. Gilman, John S. 
Billings, Charles D. Walcott, S. Weir Mitchell, John Hay, Elihu Root, and Carroll D. 
Wright, or any four of them, at the city of Washington, in the District of Columbia, 
by notice served in person or by mail addressed to each trustee at his place of resi- 
dence; and the said trustees, or a majority thereof, being assembled, shall organize 
and proceed to adopt by-laws, to elect officers and appoint committees, and generally 
to organize the said corporation; and said trustees herein named, on behalf of the 
corporation hereby incorporated, shall thereupon receive, take over, and enter into 
possession, custody, and management of all property, real or personal, of the cor- 
poration heretofore known as the Carnegie Institution, incorporated, as hereinbefore 
set forth under "An Act to establish a Code of Law for the District of Columbia, 
January fourth, nineteen hundred and two," and to all its rights, contracts, claims, 
and property of any kind or nature; and the several officers of such corporation, or 

xiii 



CARNEGIE INSTITUTION OF WASHINGTON 

any other person having charge of any of the securities, funds, real or personal, 
books, or property thereof, shall, on demand, deliver the same to the said trustees 
appointed by this Act or to the persons appointed by them to receive the same; 
and the trustees of the existing corporation and the trustees herein named shall 
and may take such other steps as shall be necessary to carry out the purposes of 
this Act. 

Sec. 7. That the rights of the creditors of the said existing corporation known as 
the Carnegie Institution shall not in any manner be impaired by the passage of this 
Act, or the transfer of the property hereinbefore mentioned, nor shall any liability 
or obligation for the payment of any sums due or to become due, or any claim or 
demand, in any manner or for any cause existing against the said existing corporation, 
be released or impaired; but such corporation hereby incorporated is declared to 
succeed to the obligations and liabilities and to be held liable to pay and discharge 
all of the debts, liabilities, and contracts of the said corporation so existing to the 
same effect as if such new corporation had itself incurred the obligation or liability 
to pay such debt or damages, and no such action or proceeding before any court 
or tribunal shall be deemed to have abated or been discontinued by reason of the 
passage of this Act. 

Sec. 8. That Congress may from time to time alter, repeal, or modify this Act 
of incorporation, but no contract or individual right made or acquired shall thereby 
be divested or impaired. 

Sec 9. That this Act shall take effect immediately. 

Approved, April 28, 1904 



XIV 



BY-LAWS OF THE INSTITUTION 

Adopted December 13, 1904. Amended December 13, 1910, December 13, 1912, December 10, 1937, 
December 15, 1939, December 13, 1940, December 18, 1942, and December 12, 1947 

Article I 

THE TRUSTEES 

1. The Board of Trustees shall consist of twenty-four members, with power to 
increase its membership to not more than twenty-seven members. The Trustees shall 
hold office continuously and not for a stated term. 

2. In case any Trustee shall fail to attend three successive annual meetings of the 
Board he shall thereupon cease to be a Trustee. 

3. No Trustee shall receive any compensation for his services as such. 

4. All vacancies in the Board of Trustees shall be filled by the Trustees by ballot 
at an annual meeting, but no person shall be declared elected unless he receives the 
votes of two-thirds of the Trustees present. 

Article II 

OFFICERS OF THE BOARD 

i. The officers of the Board shall be a Chairman of the Board, a Vice-Chairman, 
and a Secretary, who shall be elected by the Trustees, from the members of the 
Board, by ballot to serve for a term of three years. All vacancies shall be filled by the 
Board for the unexpired term; provided, however, that the Executive Committee 
shall have power to fill a vacancy in the office of Secretary to serve until the next 
meeting of the Board of Trustees. 

2. The Chairman shall preside at all meetings and shall have the usual powers of a 
presiding officer. 

3. The Vice-Chairman, in the absence or disability of the Chairman, shall perform 
the duties of the Chairman. 

4. The Secretary shall issue notices of meetings of the Board, record its transactions, 
and conduct that part of the correspondence relating to the Board and to his duties. 

Article III 

EXECUTIVE ADMINISTRATION 

The President 

1. There shall be a President who shall be elected by ballot by, and hold office during 
the pleasure of, the Board, who shall be the chief executive officer of the Institution. 
The President, subject to the control of the Board and the Executive Committee, 
shall have general charge of all matters of administration and supervision of all 
arrangements for research and other work undertaken by the Institution or with its 
funds. He shall prepare and submit to the Board of Trustees and to the Executive 

xv 



CARNEGIE INSTITUTION OF WASHINGTON 

Committee plans and suggestions for the work of the Institution, shall conduct its 
general correspondence and the correspondence with applicants for grants and with 
the special advisers of the Committee, and shall present his recommendations in each 
case to the Executive Committee for decision. All proposals and requests for grants 
shall be referred to the President for consideration and report. He shall have power 
to remove, appoint, and, within the scope of funds made available by the Trustees, 
provide for compensation of subordinate employees and to fix the compensation of 
such employees within the limits of a maximum rate of compensation to be 
established from time to time by the Executive Committee. He shall be ex officio a 
member of the Executive Committee. 

2. He shall be the legal custodian of the seal and of all property of the Institution 
whose custody is not otherwise provided for. He shall sign and execute on behalf 
of the corporation all contracts and instruments necessary in authorized administrative 
and research matters and affix the corporate seal thereto when necessary, and may 
delegate the performance of such acts and other administrative duties in his absence 
to the Executive Officer. He may execute all other contracts, deeds, and instruments 
on behalf of the corporation and affix the seal thereto when expressly authorized by 
the Board of Trustees or Executive Committee. He may, within the limits of his 
own authorization, delegate to the Executive Officer authority to act as custodian of 
and affix the corporate seal. He shall be responsible for the expenditure and disburse- 
ment of all funds of the Institution in accordance with the directions of the Board 
and of the Executive Committee, and shall keep accurate accounts of all receipts and 
disbursements. Following approval by the Executive Committee he shall transmit 
to the Board of Trustees before its annual meeting in December a written report of 
the operations and business of the Institution for the preceding fiscal year with his 
recommendations for work and appropriations for the succeeding calendar year. 

3. He shall attend all meetings of the Board of Trustees. 

4. There shall be an officer designated Executive Officer who shall be appointed by 
and hold office at the pleasure of the President, subject to the approval of the 
Executive Committee. His duties shall be to assist and act for the President as the 
latter may duly authorize and direct. 

5. The President shall retire from office at the end of the calendar year in which 
he becomes sixty-five years of age. 

Article IV 

MEETINGS 

1. The annual meeting of the Board of Trustees shall be held in the City of Wash- 
ington, in the District of Columbia, on the first Friday following the second Thursday 
of December in each year unless the date and place of meeting are otherwise ordered 
by the Executive Committee. 

2. Special meetings of the Board may be called by the Executive Committee by 
notice served personally upon, or mailed to the usual address of, each Trustee twent) 
days prior to the meeting. 

3. Special meetings shall, moreover, be called in the same manner by the Chairman 
upon the written request of seven members of the Board. 

xvi 



BY-LAWS OF THE INSTITUTION 
Article V 

COMMITTEES 

i. There shall be the following standing Committees, viz. an Executive Committee, 
a Finance Committee, an Auditing Committee, and a Nominating Committee. 

2. All vacancies occurring in the Executive Committee, the Finance Committee, 
the Auditing Committee, and the Nominating Committee shall be filled by the 
Trustees at the next regular meeting. In case of vacancy in the Finance Committee, 
the Auditing Committee, or the Nominating Committee, upon request of the re- 
maining members of such committee, the Executive Committee may fill such vacancy 
by appointment until the next meeting of the Board of Trustees. 

3. The terms of all officers and of all members of committees, as provided for 
herein, shall continue until their successors are elected or appointed. 

Executive Committee 

4. The Executive Committee shall consist of the Chairman and Secretary of the 
Board of Trustees and the President of the Institution ex officio and, in addition, 
five trustees to be elected by the Board by ballot for a term of three years, who shall 
be eligible for re-election. Any member elected to fill a vacancy shall serve for the 
remainder of his predecessor's term. 

5. The Executive Committee shall, when the Board is not in session and has not 
given specific directions, have general control of the administration of the affairs of 
the corporation and general supervision of all arrangements for administration, 
research, and other matters undertaken or promoted by the Institution. It shall also 
submit to the Board of Trustees a printed or typewritten report of each of its meetings, 
and at the annual meeting shall submit to the Board a report for publication. 

6. The Executive Committee shall have power to authorize the purchase, sale, 
exchange, or transfer of real estate. 

Finance Committee 

7. The Finance Committee shall consist of five members to be elected by the Board 
of Trustees by ballot for a term of three years. 

8. The Finance Committee shall have custody of the securities of the corporation 
and general charge of its investments and invested funds, and shall care for and 
dispose of the same subject to the directions of the Board of Trustees. It shall have 
power to authorize the purchase, sale, exchange, or transfer of securities and to 
delegate this power. It shall consider and recommend to the Board from time to 
time such measures as in its opinion will promote the financial interests of the 
Institution, and shall make a report at each meeting of the Board. 

Auditing Committee 

9. The Auditing Committee shall consist of three members to be elected by the 
Board of Trustees by ballot for a term of three years. 

xvii 



CARNEGIE INSTITUTION OF WASHINGTON 

10. Before each annual meeting of the Board of Trustees, the Auditing Com- 
mittee shall cause the accounts of the Institution for the preceding fiscal year to be 
audited by public accountants. The accountants shall report to the Committee, and 
the Committee shall present said report at the ensuing annual meeting of the Board 
with such recommendations as the Committee may deem appropriate. 

No m in ating Coram ittee 

ii. The Nominating Committee shall consist of the Chairman of the Board of 
Trustees ex officio and, in addition, three trustees to be elected by the Board by 
ballot for a term of three years, who shall not be eligible for re-election until after 
the lapse of one year. Any member elected to fill a vacancy shall serve for the 
remainder of his predecessor's term, provided that of the Nominating Committee 
first elected after adoption of this By-Law one member shall serve for one year, one 
member shall serve for two years, and one member shall serve for three years, the 
Committee to determine the respective terms by lot. 

12. Sixty days prior to an annual meeting of the Board the Nominating Com- 
mittee shall notify the Trustees by mail of the vacancies to be filled in membership 
of the Board. Each Trustee may submit nominations for such vacancies. Nomina- 
tions so submitted shall be considered by the Nominating Committee, and ten days 
prior to the annual meeting the Nominating Committee shall submit to members of 
the Board by mail a list of the persons so nominated, with its recommendations for 
filling existing vacancies on the Board and its Standing Committees. No other 
nominations shall be received by the Board at the annual meeting except with the 
unanimous consent of the Trustees present. 

Article VI 

FINANCIAL ADMINISTRATION 

i. No expenditure shall be authorized or made except in pursuance of a previous 
appropriation by the Board of Trustees, or as provided in Article V, paragraph 8, 
hereof. 

2. The fiscal year of the Institution shall commence on the first day of July in 
each year. 

3. The Executive Committee shall submit to the annual meeting of the Board a 
full statement of the finances and work of the Institution for the preceding fiscal 
year and a detailed estimate of the expenditures of the succeeding calendar year. 

4. The Board of Trustees, at the annual meeting in each year, shall make general 
appropriations for the ensuing calendar year; but nothing contained herein shall 
prevent the Board of Trustees from making special appropriations at any meeting. 

5. The Executive Committee shall have general charge and control of all appropria- 
tions made by the Board. Following the annual meeting each year, the Executive 
Committee may make allotment of funds for the period from January 1 to termi- 
nation of the fiscal year on June 30. It may also make allotment of funds for the 
period from July 1 to December 31 in advance of July 1. The Committee shall, 
however, have full authority for allotment of available funds to meet necessary 

xviii 



BY-LAWS OF THE INSTITUTION 

expenditures by other methods, if desirable, and transfer of balances to meet 
special needs. It shall make provision for outstanding obligations and for revertment 
of unexpended balances at termination of the fiscal year. 

6. The securities of the Institution and evidences of property, and funds invested 
and to be invested, shall be deposited in such safe depository or in the custody of 
such trust company and under such safeguards as the Finance Committee shall 
designate, subject to directions of the Board of Trustees. Income of the Institution 
available for expenditure shall be deposited in such banks or depositories as may 
from time to time be designated by the Executive Committee. 

7. Any trust company entrusted with the custody of securities by the Finance 
Committee may, by resolution of the Board of Trustees, be made Fiscal Agent of the 
Institution, upon an agreed compensation, for the transaction of the business coming 
within the authority of the Finance Committee. 

Article VII 

AMENDMENT OF BY-LAWS 

i. These by-laws may be amended at any annual or special meeting of the Board 
of Trustees by a two-thirds vote of the members present, provided written notice of 
the proposed amendment shall have been served personally upon, or mailed to the 
usual address of, each member of the Board twenty days prior to the meeting. 



XIX 



ABSTRACT OF MINUTES OF THE FIFTY-FIFTH MEETING OF 

THE BOARD OF TRUSTEES 

The annual meeting of the Board of Trustees was held in Washington, D. C, on 
Friday, December n, 1953. The Chairman, Mr. Root, presided. 

The following Trustees were in attendance: James F. Bell, Robert Woods Bliss, 
Lindsay Bradford, Omar N. Bradley, W. Cameron Forbes, Crawford H. Greenewalt, 
Caryl P. Haskins, Barklie Henry, Ernest O. Lawrence, Alfred L. Loomis, Robert A. 
Lovett, Keith S. McHugh, Roswell Miller, Henry S. Morgan, William I. Myers, 
Henning W. Prentis, Jr., David Rockefeller, Elihu Root, Jr., Henry R. Shepley, 
Charles P. Taft, and Juan T. Trippe. The President of the Institution, Vannevar 
Bush, was present. 

The minutes of the fifty-fourth meeting were approved. 

Reports of the President, the Executive Committee, the Finance Committee, the 
Auditor, the Auditing Committee, and the Nominating Committee, and of the 
Directors of Departments and Research Associates of the Institution were presented 
and considered. 

The sum of $1,847,584 was appropriated for the calendar year 1954 for expendi- 
ture under the general charge and control of the Executive Committee. 

The Chairman referred to the death of Lewis H. Weed almost a year ago and 
also to the earlier action of the Board in holding open a position in its membership 
pending the completion by Mr. Gifford of his duties as Ambassador to the Court 
of St. James's. Walter S. Gifford, of New York, N. Y., was re-elected a member of 
the Board to fill the vacancy held open for him, and Robert E. Wilson, of Chicago, 
Illinois, was elected a member of the Board to fill the other vacancy. 

Robert Woods Bliss was elected Secretary of the Board for the remainder of the 
term ending in 1954 to succeed Henry S. Morgan, who had been serving under an 
interim appointment. Caryl P. Haskins and Barklie Henry were re-elected members 
of the Executive Committee for three-year terms, and Henry S. Morgan was elected 
a member of the Executive Committee for the remainder of the term of Mr. Bliss, 
expiring in 1954, as the Secretaryship carries with it ex-officio membership in the 
Executive Committee. Lindsay Bradford was re-elected Chairman and member of 
the Finance Committee to serve for three years, and Henning W. Prentis, Jr., was 
re-elected a member of the Finance Committee to serve for three years. Keith S. 
McHugh was elected a member of the Nominating Committee for a period of three 
years, succeeding Robert Woods Bliss. 



XXI 



REPORT OF THE EXECUTIVE COMMITTEE 
For the Year Ended June 30, 1953 

To the Trustees of the Carnegie Institution of Washington: 

Gentlemen: In accordance with the provisions of the By-Laws, the Executive 
Committee submits this report to the annual meeting of the Board of Trustees. 

During the fiscal year ended June 30, 1953, the Executive Committee held four 
meetings, printed reports of which have been mailed to each Trustee and constitute 
a part of this report. 

The detailed record of the activities of the Institution is presented in the reports 
from the Departments, which are contained in the Year Book, a review of some of 
the highlights being given in the report of the President. The estimate of expendi- 
tures for the calendar year 1954 contained in the report of the President has been 
considered and approved by the Executive Committee, and the Committee has also 
provisionally approved and recommends to the Board the proposed budget based 
thereon. 

The Board of Trustees, at its meeting of December 12, 1952, appointed the firm of 
Haskins & Sells to audit the accounts of the Institution for the fiscal year ending June 
30, 1953. The report of the Auditor, including a balance sheet showing assets and 
liabilities of the Institution on June 30, 1953, together with supporting statements and 
schedules, is submitted as a part of the report of the Executive Committee. 

Two vacancies exist in the membership of the Board of Trustees: one vacancy left 
unfilled since the resignation of Mr. Walter S. Gifford in 1950, and the other resulting 
from the death of Dr. Lewis H. Weed on December 21, 1952. 

A vacancy in the office of Secretary of the Board of Trustees, resulting from the 
death of Dr. Weed, has been filled by the Executive Committee through the tem- 
porary appointment of Mr. Morgan, until the forthcoming annual meeting of the 
Board of Trustees. The terms of Dr. Haskins and Mr. Henry as members of the 
Executive Committee will end at the annual meeting. The terms of Mr. Bradford 
(Chairman) and of Mr. Prentis as members of the Finance Committee will also end 
at the annual meeting. The term of Mr. Bliss as a member of the Nominating Com- 
mittee will likewise end at the annual meeting. 

Elihu Root, Jr., Chairman 
October 22, ig^ 



xxin 



HASKINS & SELLS 500 Equitable Building 

Certified Public Accountants Baltimore 2 



ACCOUNTANTS' CERTIFICATE 

To the Board of Trustees of Carnegie Institution of Washington: 

We have examined the balance sheet of Carnegie Institution of Washington as of 
June 30, 1953 and the related summaries of current income and expenditures, current 
funds surplus, current restricted gifts and grants, changes in endowment and other 
special funds, and changes in investment in real estate and equipment for the year 
then ended (Exhibits A to F, inclusive). Our examination was made in accordance 
with generally accepted auditing standards, and included such tests of the accounting 
records and such other auditing procedures as we considered necessary in the circum- 
stances, except that we did not examine the records in support of expenditures made 
(approximately $266,000) by five of the seven branch offices of the Institution, but we 
have reviewed internal audit reports of the Bursar's office covering examinations of 
all branch records during the year. 

In our opinion, subject to the exception stated above with respect to the limitation 
of the scope of our examination, the accompanying balance sheet and above described 
summaries (Exhibits A to F, inclusive) present fairly the financial position of the 
Institution at June 30, 1953 and the results of its operations for the year then ended, 
in conformity with generally accepted accounting principles applied on a basis con- 
sistent with that of the preceding year. 

Haskins & Sells 
August 31, 1953 



XXV 



Exhibit A Balance Sheet, June 30, 1953 

Assets 
Current Funds: 

Cash in banks and on hand $594,117.64 

Advances: 

Departmental Research Operations 13,330.78 

Other 423.73 

Accounts receivable 469.01 

Inventory of books 89,924.00 

Deferred charges 23,250.49 

Due from Endowment and Other Special Funds 343,939.44 $1,065,455.09 



Endowment and Other Special Funds: 

Cash in banks $286,954.59 

Securities (valuation based on market quota- 
tions at June 30, 1953— $50,224,304)— 
Schedule 1: 

Bonds $25,250,223.88 

Preferred stocks 4,073,132.15 

Common stocks 15,119,908.90 44,443,264.93 44,730,219.52 



Plant Funds: 

Investment in real estate and equipment — Exhibit F 5,049,163.44 



Total $50,844,838.05 



Liabilities 

Current Funds: 

Accounts payable $2,559.33 

Reserve for valuation of books and accounts receivable 90,393.01 

Current Funds Surplus — Exhibit C: 

Appropriated unexpended balances $448,531.15 

General Contingent Fund 492,321.45 940,852.60 



Unexpended balance of restricted gifts and grants — Exhibit D 31,650.15 $1,065,455.09 



Endowment and Other Special Funds: 

Due to Current Funds $343,939.44 

Principal of Funds — Exhibit E: 

Capital funds $41,379,485.59 

Special funds 3,006,794.49 44,386,280.08 44,730,219.52 



Plant Funds: 

Bequests, gifts, and income invested in plant $4,991,159.04 

Harriman Fund — donated land 17,934.40 

Harkavy Fund — donated land 2,070.00 

Hale Fund— Solar Laboratory 38,000.00 5,049,163.44 



Total $50,844,838.05 



XXVI 



Exhibit B Summary of Current Income and Expenditures 

For the Year Ended June 30, 1953 

Current Income: 

Investment income: 

Interest and dividends on securities $1,943,224.04 

Less: Amortization of bond premiums 25,935.94 $1,917,288.10 



Market value of stock dividend 13,137.00 



Total— Schedule 1 $1,930,425.10 

Less: Income added to Special Funds (Exhibit E) — Schedule 1 1,485.66 



Remainder — Income available for current purposes $1,928,939.44 

Other income: 

Sales of publications $5,030.95 

Dormitory and mess hall 9,125.01 

Miscellaneous 605.00 14,760.96 



Restricted gifts and grants utilized for current purposes — Exhibit D 60,932.75 



Total current income $2,004,633.15 

Current Expenditures (including expenditures against appropri- 
ations of prior years) — Schedule 4: 

Administration $231,245.79 

Departmental Research Operations 1,312,527.64 

General Publications 29,450.39 

Research Projects, Fellowships, Grants, etc 79,590.13 

Pension Fund — annuity and insurance 156,369.46 



$1,809,183.41 
Gifts and grants— Exhibit D 60,932.75 



Total current expenditures 1,870,116.16 



Excess of current income over current expenditures — Exhibit C $134,516.99* 



*SUMMARIZED AS FOLLOWS: 

Current investment income in excess of Trustees' authorized 
appropriations during the fiscal year, credited to General 
Reserve Fund— Exhibit E $87,250.44 

Market value of stock dividend credited to Special Income 

Reserve— Exhibit E 13,137.00 

Revertment of unexpended current appropriations to General 

Contingent Fund— Schedule 4 92,720.54 

Reserved from this year's appropriations for current liabilities 

and commitments — Schedule 4 124,087.49 



Total $317,195.47 

Less: Amount included in current expenditures, applicable to 
allotments and unexpended balances from prior years' 
appropriations— Schedule 4 182,678.48 $134,516.99 



xxvn 



Exhibit C Summary of Current Funds Surplus 

For the Year Ended June 30, 1953 

Balance, July 1, 1952 $902,323.05 

Additions: 

Excess of current income over current expenditures — Exhibit B . . $134,516.99 
Transfer from Special Funds (General Reserve Fund) to cover 
miscellaneous expenditures in connection with the building 
program at Cold Spring Harbor— Exhibit E 4,400.00 138,916.99 



Total $1,041,240.04 



Deductions: 

Transfer to Special Funds — Exhibit E: 

General Reserve Fund, representing excess of investment in- 
come over Trustees' appropriations for current purposes. . $87,250.44 
Special Income Reserve, representing market value of stock 

dividend received during year 13,137.00 100,387.44 



Balance, June 30, 1953, per Schedule 3 $940,852.60 



XXVlll 



Exhibit D Summary of Current Restricted Gifts and Grants 

For the Year Ended June 30, 1953 

Unexpended Additions — Deductions — Unexpended 

Balance Gifts and Grants Expenditures Balance 

July 1, 1952 Received (Schedule 4) June 30, 1953 
Departmental Research Operations: 

Department of Plant Biology: 

Research Corporation $1,125.47 $1,125.47 

Department of Genetics: 

American Cancer Society No. EG 2 IE 175.10 $7,400.00 $6,904.06 671.04 

American Cancer Society No. 

INSTR-72 4,000.00 4,000.00 

U. S. Public Health Service No. 

RG-149 C6 2,549.62 8,804.40 8,087.41 3,266.61 

U. S. Public Health Service No. 

E-133 C2 2,762.94 8,415.26 10,430.22 747.98 

National Foundation for Infantile 

Paralysis 600.00 600.00 

Department of Embryology: 

American Cancer Society No. CP 2F 206.50 206.50 



U. S. Public Health Service No. 

C550-C4 4,747.78 4,747.78 



Research Projects, Fellowships, etc.: 

Carnegie Corporation of New York: 

Biology: 

Point Lobos, California 4,245.32 

Yerkes Laboratories of Primate 

Biology 12,000.00 

Geology : 

Tilley, C. E 620.63 

History: 

Dantzig, Tobias 8,000.00 

Physiology: 

Russell, G. Oscar 1,522.44 

Plant Biology: 

Chlorella studies 11,979.02 

Terrestrial Magnetism: 

Magnetic polarization of the earth 4,428.42 

Clews, C. J. Birkett 7,500.00 

Miscellaneous: 

Hale, George Ellery, biography . . . 1,000.00 

National Academy of Sciences: 

Tamiya, Hiroshi 500.00 



12,000.00 . 






620.63 


4,000.00 


4,000.00 


300.00 


1,222.44 


9,500.00 


2,479.02 


1,887.88 


2,540.54 


1,368.90 


6,131.10 


1,000.00 




500.00 





Total $43,363.24 $49,219.66 $60,932.75 $31,650.15 



XXIX 



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XXXI 



Schedule 1 Endowment and Other Special Funds Investments as of 

June 30, 1953 and Income Therefrom during the Year 



Per Cent of 
Total Investments 

, * N 

Book Market Income 

Book Value Market Value Value Value Received 
Bonds: 

United States Government.... $10,809,443.35 $10,512,542 24.17% 20.81% $218,136.64 

Foreign and International Bank 1,174,158.03 1,113,375 2.62% 2.21% 34,383.35 

Public Utility 3,322,568.99 3,092,252 7.43% 6.12% 83,514.97 

Communication 1,339,184.59 1,288,312 2.99% 2.55% 36,374.57 

Railroad 641,530.52 651,855 1.43% 1.29% 26,137.69 

Railroad Equipment Trust.... 1,075,956.31 1,022,468 2.41% 2.02% 23,708.16 

Industrial and Miscellaneous.. 6,887,382.09 6,461,542 15.40% 12.80% 160,571.31 

Total bonds $25,250,223.88 $24,142,346 56.45% 47.80%, $582,826.69* 

Stocks : 

Preferred $4,073,132.15 $3,714,826 9.11% 7.35% $167,379.70 

Common 15,119,908.90 22,367,132 33.80%, 44.28% l,180,218.71f 

Total stocks $19,193,041.05 $26,081,958 42.91% 51.63% $1,347,598.41 

Cash $286,954.59 $286,954 .64% .57% 

Total $44,730,219.52 $50,511,258 100.00% 100.00% $1,930,425.10$ 



* After deducting bond premium amortization of $25,935.94. 

t Includes $13,137.00 representing market value of a stock dividend received. 

% Income received allocated to Endowment and Other Special Funds as follows: 

Funds, the income from which may be used for current general purposes — Exhibit B $1,928,939.44 

Funds, the income from which is restricted to specific purposes — Exhibit E: 

Bickel Fund $443.09 

George E. Hale Relief Fund 162.87 

Harkavy Fund 123.40 

Woloff Fund 756.30 1,485.66 

Total $1,930,425.10 



XXXU 



Schedule 2 



Schedule of Securities 



Principal 
amount 



Description 



Approximate 
Ma- Book market 

turity value value 



United States Government Bonds 

$220,000 U. S. of America Treasury Bills 7-30-53 

550,000 U. S. of America Treasury Ctf. of Ind. 2s 8-15-53 

1,500,000 U. S. of America Treasury Ctf. of Ind. 2 ]/ A s 2-15-54 

1,550,000 U. S. of America Treasury Notes 2 yis 1953 

1,700,000 U. S. of America Treasury 2s 1954-52 

3,150,000 U. S. of America Treasury 2 J4s 1962-59 

1,000,000 U. S. of America Treasury 2 Hs 1980-75 

400,000 U. S. of America Treasury 3 J4s 1983-78 

50,000 U. S. of America Savings Series "G" 2 }4s 1954 

50,000 U. S. of America Savings Series "G" 2 }4s 1954 

100,000 U. S. of America Savings Series "G" 2 J4s 1955 

100,000 U. S. of America Savings Series "G" 2 l / 2 s 1956 

100,000 U. S. of America Savings Series "G" 2 yis 1957 

100,000 U. S. of America Savings Series "G" 2 Ks 1958 

100,000 U. S. of America Savings Series "G" 2 Ks 1959 

100,000 U. S. of America Savings Series "G" 2 yis 1960 

$10,770,000 Total U. S. Government 



$218,884.11 


$219,709 


550,000.00 


550,110 


1,502,343.75 


1,499,062 


1,548,026.10 


1,550,000 


1,700,000.00 


1,688,843 


3,199,095.64* 


2,978,718 


991,093.75 


948,750 


400,000.00 


398,750 


50,000.00 


49,600 


50,000.00 


49,300 


100,000.00 


98,200 


100,000.00 


97,600 


100,000.00 


97,000 


100,000.00 


96,400 


100,000.00 


95,800 


100,000.00 


94,700 


$10,809,443.35 


$10,512,542 



$300,000 
100,000 
50,000 
100,000 
125,000 
125,000 
150,000 
200,000 



$1,150,000 



Foreign and International Bank Bonds 

Aluminum Company of Canada, Ltd., S. F. Deb. 3 Hs 

Australia, Commonwealth of, S. F. 3 yis 

Australia, Commonwealth of, S. F. 3 yis 

Canadian National Ry. Co., 4>2S Guar 

International Bank for Reconstruction and Development, 3s. . 
International Bank for Reconstruction and Development, 3 ¥&s 

Noranda Mines Ltd., S. F. Deb. 4 ^s 

Shawinigan Water & Power Co., 1st Mtg. & Coll. Tr. S. F. 3s 
Series "M" 

Total Foreign and International Bank 



1970 


$304,256.16* 


$304,500 


1956 


100,000.00 


98,250 


1957 


48,750.00 


48,500 


1957 


112,000.00 


104,625 


1976 


125,000.00 


114,375 


1975 


123,125.00 


119,375 


1968 


154,546.87 


150,000 


1971 


206,480.00* 


173,750 




$1,174,158.03 


$1,113,375 



Public Utility Bonds 

$200,000 American Gas & Electric Co., Serial Note 2 yis 1954-55 

125,000 Columbia Gas System, Inc., Deb. 3s 1975 

237,000 Columbus & Southern Ohio Electric Co., 1st Mtg. 3 Xs 1970 

300,000 Consolidated Natural Gas Co., Deb. 2 Hs 1968 

150,000 Detroit Edison Co., Gen. & Ref. Mtg. 3 pis 1988 

200,000 Minnesota Power & Light Co., 1st Mtg. 3 yis 1975 

200,000 Northern Natural Gas Co., Serial Deb. 2 Hs 1954-55 

100,000 Ohio Power Co., 1st Mtg. 3}{s 1968 

200,000 Pacific Gas and Electric Co., 1st & Ref. Mtg. 4s 1984 

200,000 Panhandle Eastern Pipe Line Co., Serial Deb. 2 Hs 1961-62 

100,000 Panhandle Eastern Pipe Line Co., S. F. Deb. 3Xs 1973 

50,000 Philadelphia Electric Co., 1st & Ref. Mtg. 2 V&s 1978 

207,000 Philadelphia Electric Power Co., 1st Mtg. 2 ^s 1975 

200,000 Public Service Co. of Indiana, Inc., 1st Mtg. 3 yis 1975 

45,000 Puget Sound Power & Light Co., 1st Mtg. 4><s 1972 

210,000 Tennessee Gas & Transmission Co., 1st Mtg. Pipe Line 2Ks. • 1966 

191,000 Tennessee Gas Transmission Co., 1st Mtg. Pipe Line 3s 1969 

93,000 Tennessee Gas Transmission Co., S. F. Deb. 4^s 1971 

265,000 United Gas Corp., 1st Mtg. & Coll. Tr. 2 #s 1967 

$3,273,000 Total Public Utility 



$201,949.46* 


$197,320 


128,002.01* 


114,375 


247,970.16* 


220,410 


300,647.56* 


286,500 


152,250.00 


153,750 


203,658.13* 


182,000 


201,891.24* 


198,210 


101,500.00 


100,625 


203,560.00 


205,750 


201,625.43* 


183,600 


101,447.02* 


94,000 


49,687.50 


45,000 


210,846.72* 


178,020 


203,700.32* 


184,000 


46,209.73* 


46,800 


212,047.50* 


191,100 


195,640.42* 


171,900 


94,935.79* 


95,092 


265,000.00 


243,800 


$3,322,568.99 


$3,092,252 



* After deduction for amortization of premiums on bonds purchased subsequent to January 1, 1940. 



XXX111 



Schedule of Securities — Continued 

Principal Ma- 
amount Description turity 

Communication Bonds 

$150,000 American Telephone & Telegraph Co., Conv. Deb. 2 Ms 1961 

150,000 American Telephone & Telegraph Co., Deb. 2 Ms 1975 

200,000 American Telephone & Telegraph Co., Conv. Deb. 3 Ms 1963 

200,000 Mountain States Telephone & Telegraph Co., Deb. 3 Ms 1978 

100,000 New York Telephone Co., Ref. Mtg. 3 Ms 1978 

200,000 Pacific Telephone & Telegraph Co., Deb. 3 Ms 1978 

300,000 Southwestern Bell Telephone Co., Deb. 3 Ms 1983 

$1,300,000 Total Communication 

Railroad Bonds 

$100,000 Chesapeake & Ohio Ry. Co., Gen. Mtg. 4 Ms 1992 

284,000 Fort Worth & Denver Rwy. Co., 1st Mtg. 4 Ms 1982 

100,000 Pennsylvania R. R. Co., Cons. Mtg. 4 Ms 1960 

143,000 Western Maryland Rwy. Co., 1st Mtg. 4 Ms 1976 

$627,000 Total Railroad 

Railroad Equipment Trust Bonds 

$150,000 Chesapeake & Ohio Ry. Co., Eq. Tr. 2s Guar 1956-58 

300,000 Chicago Burlington & Quincy R. R. Co., Eq. Tr. 2 Ms Guar... 1958-63 

100,000 Great Northern Railway Co., Eq. Tr. 2s Guar 1960-61 

150,000 Pennsylvania R. R. Co., Eq. Tr. 2 Ms Guar 1958-62 

100,000 Southern Pacific Co., Eq. Tr. 2 Ms Guar 1956 & 59 

150,000 Southern Pacific Co., Eq. Tr. 2 Ms Guar 1956-58 

150,000 Southern Railway Co., Eq. Tr. 2 Ms Guar 1956-58 

$1,100,000 Total Railroad Equipment Trust 

Industrial and Miscellaneous Bonds 

$200,000 Allied Chemical and Dye Corp., Deb. 3 Ms 1978 

200,000 Aluminum Company of America, S. F. 3 Ms 1964 

187,000 American Tobacco Co., Deb. 3s 1969 

234,000 Bristol Myers Co., Deb. 3s 1968 

300,000 C. I. T. Financial Corp., Deb. 2 Ms 1959 

150,000 Dow Chemical Co., Deb. 2.35s 1961 

130,000 Dow Chemical Co., Conv. Sub. Deb. 3s 1982 

153,000 Food Machinery Corp., S. F. Deb. 2 Ms 1962 

275,000 Goodrich (B. F.) Company, 1st Mtg. 2 Ms 1965 

255,000 P. Lorillard Co., Deb. 3s 1963 

295,000 National Dairy Products Corp., Deb. 2 Ms 1970 

488,000 Phillips Petroleum Co., S. F. Deb. 2 Ms 1964 

200,000 Phillips Petroleum Co., Conv. S. F. Deb. 3.70s 1983 

125,000 Pittsburgh Plate Glass Co., S. F. Deb. 3s 1967 

150,000 Quaker Oats Co., Deb. 2 Ms 1964 

300,000 Seagram (Joseph E.) & Sons, Inc., Deb. 2 Ms 1966 

300,000 Service Pipe Line Co., S. F. Deb. 3.20s 1982 

500,000 Shell Union Oil Corp., Deb. 2 Ms 1971 

200,000 Sinclair Oil Corp., Conv. Sub. Deb. 3 Ms 1983 

500,000 Socony- Vacuum Oil Co., Inc., Deb. 2 Ms 1976 

100,000 Standard Oil Co., (Ind.) Conv. Deb. 3 Ms 1982 

300,000 Swift & Co., Deb. 2 Ms 1972 

500,000 Texas Corporation, Deb. 3s 1965 

346,000 Union Oil Company of California, Deb. 2 Ms 1970 

57,000 Union Oil Company of California, Conv. Sub. Deb. 3 Ms 1972 

400,000 Westinghouse Electric Corporation, Deb. 2 Ms 1971 

$6,845,000 Total Industrial and Miscellaneous 

$25,065,000 Bonds — Funds Invested 



* After deduction for amortization of premiums on bonds purchased subsequent to January 1, 1940. 

xxxiv 



Approximate 


Book 


market 


value 


value 


$153,113.91* 


$164,062 


151,968.75* 


135,000 


220,853.78* 


230,250 


201,400.00* 


194,000 


101,183.45* 


94,500 


204,414.70* 


190,000 


306,250.00* 


280,500 


$1,339,184.59 


$1,288,312 


$99,464.29 


$112,000 


286,749.97* 


285,420 


104,662.50 


105,000 


150,653.76* 


149,435 


$641,530.52 


$651,855 


$146,340.34 


$142,290 


292,507.12 


274,660 


98,538.91 


89,725 


146,358.96 


137,523 


100,031.19* 


93,730 


146,251.10 


142,565 


145,928.69 


141,975 


$1,075,956.31 


$1,022,468 


$198,000.00 


$200,000 


200,000.00 


199,750 


189,236.11* 


181,623 


234,869.74* 


225,810 


300,000.00* 


283,500 


150,511.37* 


141,750 


131,922.84* 


128,537 


152,308.98 


140,760 


275,796.09* 


262,625 


260,387.35* 


247,350 


298,485.24* 


271,400 


492,889.73* 


463,600 


206,750.00 


209,250 


125,000.00 


121,250 


148,922.50 


139,500 


298,500.00 


279,000 


300,000.00 


288,000 


503,666.21* 


452,500 


192,416.25 


193,750 


489,528.75 


437,500 


101,286.72* 


100,875 


301,351.57* 


267,000 


519,645.49* 


498,750 


355,313.95* 


318,320 


57,000.00 


57,142 


403,593.20* 


352,000 


$6,887,382.09 


$6,461,542 


$25,250,223.88 


$24,142,346 



Number of 
shares 



Schedule of Securities — Continued 



Description 



Book 
value 



Approximate 

market 

value 



400 
1,000 
1,500 
2,000 
1,500 

500 

600 
1,900 
1,125 
1,000 

600 
2,075 
1,000 
2,000 
1,500 
1,000 
1,000 

300 

800 
2,000 
1,300 
1,500 
1,000 

900 
2,000 

760 
1,300 
3,100 



35,660 



2,000 
5,300 

19,360 
2,600 

10,250 
2,850 
3,000 
4,700 
2,800 
7,500 
5,200 
2,000 
60 
1,500 
5,400 
2,000 
2,750 
1,250 
6,373 

12,200 
1,000 
3,500 
6,100 
4,800 
7,980 
2,500 
3,620 



Preferred Stocks 

Air Reduction Company, Inc., 4.50% Cum. Conv. Pref $41,195.04 

Anchor Hocking Glass Corp., $4.00 Cum. Pref 1 12,750.00 

Appalachian Electric Power Co., 4K% Cum. Pref 159,000.00 

Armstrong Cork Co., $3.75 Cum. Pref 205,500.00 

Bethlehem Steel Corp., 7% Cum. Pref 183,637.50 

Case (J. I.) Co., 7% Cum. Pref 62,225.00 

Cleveland Electric Illuminating Co., $4.50 Cum. Pref 68,112.25 

Consolidated Edison Co. of N. Y., Inc., $5.00 Cum. Pref 202,815.50 

Continental Can Co., Inc., $3.75 Cum. Pref 115,312.50 

Continental Can Co., Inc., $4.25 Cum. Conv. 2nd Pref 106,779.99 

Corn Products Refining Co., 7% Cum. Pref 110,335.18 

duPont (E. I.) de Nemours & Co., $4.50 Cum. Pref 235,401.89 

El Paso Natural Gas Co., 4.10% Cum. Pref 111,442.21 

General Foods Corp., $3.50 Cum. Pref 201,000.00 

General Motors Corp., $5.00 Cum. Pref 187,937.50 

General Shoe Corporation, $3.50 Cum. Pref 102,250.00 

Grant (W. T.) Co., 3 H% Cum. Pref 100,447.91 

Merck & Co., Inc., $4.00 Conv. Cum. 2nd Pref 31,200.00 

National Distillers Products Corp., \ l A% Cum. Conv. Pref 80,000.00 

Niagara Mohawk Power Corp., 3.60% Cum. Pref 207,990.00 

Ohio Power Co., 4K% Cum. Pref 144,630.02 

Pacific Telephone and Telegraph Co., 6% Cum. Pref 235,220.75 

Panhandle Eastern Pipe Line Co., 4% Cum. Pref 104,166.68 

Pillsbury Mills, Inc., $4.00 Cum. Pref 96,949.80 

Reynolds (R. J.) Tobacco Co., 3.60% Cum. Pref 199,683.75 

Sherwin-Williams Co., 4% Cum. Pref 83,764.83 

Standard Oil Co. of Ohio, 3 H% Cum. Pref. "A" 139,976.28 

U. S. Steel Corp., 7% Cum. Pref 443,407.57 

Total Preferred Stocks $4,073,132.15 

Common Stocks 

Allied Chemical & Dye Corp $96,175.97 

Aluminium Limited 221,852.22 

American Can Company 445,351.97 

American Cyanamid Co 161,924.48 

American Gas and Electric Company 214,294.48 

American Telephone & Telegraph Co 413,951.54 

Anderson, Clayton & Co 164,768.84 

Armstrong Cork Company 231,516.80 

Atchison, Topeka and Santa Fe Rwy. Co 232,758.69 

C. I. T. Financial Corporation 151,369.19 

Caterpillar Tractor Co 272,536.55 

Chase National Bank of the City of New York 71,361.04 

Christiana Securities Co 356,143.00 

Chrysler Corporation 68,005.61 

Cleveland Electric Illuminating Company 227,773.54 

Consolidated Edison Company of N. Y., Inc 67,530.37 

Consumers Power Co 94,687.50 

Continental Illinois National Bank & Trust Co. of Chicago 88,175.00 

Continental Insurance Co 241,723.37 

Continental Oil Co. of Delaware 239,598.64 

Corning Glass Works 59,631.83 

Deere & Company 117, 181. 35 

Delaware Power & Light Company 128,803.87 

duPont (E. I.) de Nemours & Co 195,905.06 

Eastman Kodak Co 209,388.59 

Fidelity-Phenix Fire Insurance Co. of New York 171,032.77 

Fireman's Fund Insurance Co 128,858.78 



$41,200 

94,250 

148,500 

180,000 

205,500 

62,500 

61,500 

202,350 

98,437 

122,000 

98,550 

229,287 

90,000 

178,000 

174,937 

85,000 

86,750 

28,275 

71,200 

161,750 

128,050 

195,000 

94,500 

86,400 

169,000 

75,240 

123,500 

423,150 

$3,714,826 



$135,000 
251,087 
672,760 
115,700 
292,125 
437,831 
104,625 
250,275 
259,350 
196,875 
273,000 

90,500 
379,500 
107,625 
270,000 

75,750 
101,750 
103,437 
452,483 
674,050 

76,250 

91,000 
147,925 
455,400 
334,162 
177,500 
193,670 



{Concluded on following page) 
XXXV 



Number of 
shares 



9,000 
4,000 
6,000 
3,000 
2,000 

14,352 

10,625 
1,800 
2,567 

11,300 
2,500 
2,800 
7,940 
3,470.5 
5,000 
1,800 
2,000 
9,000 
5,000 
7,000 
320 
8,000 

11,925 
7,000 
5,500 
3,000 
1,300 
2,300 

10,000 
8,000 
3,300 
7,000 
1,000 
4,000 
2,400 
3,990 
7,800 
4,200 
5,200 
2,600 

11,000 
500 
4,800 
9,900 
5,000 
7,800 
6,200 
6,200 
5,500 
800 
1,800 
8,050 
4,000 
4,750 
4,000 
4,700 
8,500 
1,700 

433,782.5 

469,442.5 



Schedule of Securities — Continued 

Approximate 

Book market 

Description value v^lue 

Common Stocks — Continued 

General Electric Co $354,865.31 $639,000 

General Foods Corporation 167,302.84 213,000 

General Motors Corporation 159,935.38 359,250 

Goodrich (B. F.) Company 155,957.20 200,250 

Guaranty Trust Co. of N. Y 98,003.91 126,000 

Gulf Oil Corp 310,532.07 640,458 

Gulf States Utilities Co 223,614.04 233,750 

Halliburton Oil Well Cementing Co 79,847.34 97,650 

Hartford Fire Insurance Co 173,120.24 386,333 

Humble Oil & Refining Co •. 188,600.61 700,600 

Illinois Power Co 97,697.35 95,000 

Inland Steel Company 156,896.54 109,550 

Insurance Company of North America 243,482.20 647,110 

International Business Machines Corp 213,004.45 798,215 

International Nickel Co. of Canada, Ltd 185,533.15 208,750 

International Paper Company 95,379.27 91,800 

Johns-Manville Corp 74,008.06 120,500 

Kennecott Copper Corporation 459,524.19 577,125 

Kimberly-Clark Corporation J 227,813.88 200,000 

Kresge (S. S.) Company 220,699.69 235,375 

Mellon National Bank and Trust Company 67,193.07 100,800 

Mercantile Stores Company, Inc 174,200.45 140,000 

Merck & Co., Inc 223,709.20 232,537 

Middle South Utilities, Inc 168,660.65 177,625 

Minneapolis-Honeywell Regulator Co 127,075.73 313,500 

Monsanto Chemical Co 126,552.58 258,000 

Montgomery Ward & Co., Inc 70,154.45 76,700 

National City Bank of New York 88,539.38 112,700 

Newberry (J. J.) Co 132,451.57 320,000 

North American Co 155,852.66 158,000 

Ohio Edison Co 105,150.00 122,100 

Penney (J. C.) Co 248,413.74 479,500 

Peoples Gas Light and Coke Company 106,350.00 130,500 

Pfizer (Chas.) & Co., Inc 82,503.08 112,500 

Phelps Dodge Corporation -. 71,057.69 76,500 

Philip Morris & Co., Ltd., Inc 210,697.55 199,500 

Pittsburgh Plate Glass Co ' 251,672.40 378,300 

Procter & Gamble Co 177,227.28 251,475 

Scott Paper Co 137,909.13 308,100 

Seaboard Oil Co. of Delaware 229,104.22 213,200 

Sears, Roebuck & Co 251,140.45 646,250 

Security-First National Bank of Los Angeles 35,039.88 50,000 

Sherwin-Williams Co 294,227.78 321,600 

Socony- Vacuum Oil Co., Inc 300,464.13 346,500 

Southern California Edison Company 175,996.33 171,250 

Standard Oil Co. of Indiana 282,824.78 560,625 

Standard Oil Co. of New Jersey : 197,233.38 442,525 

Texas Company 163,636.60 328,600 

Union Carbide & Carbon Corp 172,416.63 353,375 

Union Electric Co. of Missouri 16,787.72 17,500 

United Fruit Company 51,075.58 95,400 

United Gas Corp 127,987.59 193,200 

United States Gypsum Co 362,416.20 426,000 

United States Plywood Corporation 174,129.76 119,937 

United States Steel Corporation 188,577.48 154,000 

Virginia Electric and Power Co 92,038.13 109,862 

Westinghouse Electric Corp 232,369.41 376,125 

Weyerhaeuser Timber Company 88,953.47 93,500 

Total Common Stocks $15,119,908.90 $22,367,132 

Common and Preferred Stocks — Funds Invested $19,193,041.05 $26,081,958 

Aggregate Investments (Bonds and Stocks) $44,443,264.93 $50,224,304 



XXXVI 



Schedule of Securities — Concluded 

Summary of Security Transactions July 1, 1952 to June 30, 1953 
Cash awaiting investment — July 1, 1952 $122,175.65 



Bonds 

Preferred Stocks 

Common Stocks 

Sale of Stock Rights. 



Net Gain — To Exhibit E. 



Sales and Redemptions 



Gain 



Loss 



Book Value 



$5,521.16 

1,395,428.68 

29,134.82 

$1,430,084.66 



$25,461.51 $3,142,425.89 

165,458.90 

1,588,283.18 



$25,461.51 
1,404,623.15 



$1,430,084.66 $1,430,084.66 



Income applied to amortization of bond premiums. 
Market value of stock dividend 



Total 

Less: Cash transferred for current needs. 



14,896,167.97 
1,404,623.15 



6,300,791.12 



25,935.94 
13,137.00 

1,462,039.71 
200,000.00 



Remainder . 



),262,039.71 



A cquisitions 

Bonds $5,441,286.65 

Common Stocks 533,798.47 



Cash awaiting investment — June 30, 1953 



5,975,085.12 
$286,954.59 



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XXXIX 



REPORT OF THE PRESIDENT 



OF THE 



CARNEGIE INSTITUTION OF WASHINGTON 



FOR THE YEAR ENDING JUNE 30, 1953 



REPORT OF THE PRESIDENT 

OF THE 

CARNEGIE INSTITUTION OF WASHINGTON 



This Institution has a magnificent op- 
portunity in the future if national condi- 
tions are such that it can continue to 
prosper, for the fields of fundamental re- 
search in which it is engaged are by no 
means exhausted or running into a phase 
of diminishing returns. They offer in fact 
many fine new vistas. 

In astronomy we are just beginning to 
reap the benefits of exceedingly powerful 
instrumentation — to explore the far reaches 
of the universe, assign it a revised measure 
of magnitude, and throw light perhaps on 
its ultimate geometry and its apparent ex- 
pansion. With spectroscopy of enhanced 
discrimination, we approach with new ef- 
fectiveness the problems of the composition 
of the universe and its evolution. As radio 
astronomy joins optical methods, we see 
things that are not visible to the eye or 
even to the photographic plate. 

The genetics of lower organisms is lead- 
ing us deep into a new understanding of 
the earlier phases of life processes, yet far 
from the beginnings of life itself; for even 
in bacteria and viruses the complexities of 
the mechanisms of inheritance have been 
found to be far greater than might have 
been anticipated. The use of tracer tech- 
niques, the speed and versatility of chroma- 
tography, the extension of microscopy, the 
selection of a few unique individuals 
among billions by the use of phages — all 
open up the possibility of understanding 
better many of the life processes in their 
more fundamental forms: the basic func- 
tioning of the genetic system, the synthesis 
of amino acids and the proteins, the de- 
velopment of the human egg and embryo, 
and much more. The day is coming when 



man will use lower organisms far more 
than he does today to produce food, to 
separate raw materials from the sea for 
his use, to synthesize the complex organic 
compounds necessary for his industry and 
for his physical well-being. Basic to this 
use is an understanding of the funda- 
mental life processes, and here is where 
the Institution's interest lies, rather than in 
the application. There is evident oppor- 
tunity for another fifty years of exacting 
endeavor in elaborating a constantly wid- 
ening set of concepts. 

Nor are we by any means far along in 
our understanding of the planet on which 
we perform such extraordinary investiga- 
tions — its sea of air above with its chemi- 
cal, meteorological, and electrical phenom- 
ena; the earth beneath with its rocks, its 
continents floating on a viscous mass, its 
mountain building, and its mysterious 
magnetic core. Here too the advance of 
instrumentation provides new tools, elec- 
tronic in nature to a large extent but also 
chemical and physical in the more classic 
sense. We wish to know how the earth 
evolved into its present state, how it is now 
composed, how to account for the mag- 
netic and electrical performance we wit- 
ness, how our occupancy of it will affect 
some of its key features in the future. 
Out of this may come better communica- 
tions, new sources of materials, other 
things that man desires. But we are chiefly 
interested because we are human and have 
an inherent urge to understand ourselves 
and our environment. 

The Institution thus has a varied and 
fascinating future within its present scien- 
tific fields if it retains its virility and its 



CARNEGIE INSTITUTION OF WASHINGTON 



skills. But will it be able to proceed as the 
scene about it alters? It has thus far pros- 
pered, and it has grown in strength and 
distinction. 

It is sometimes maintained that the day 
of the independent research institution is 
over, that henceforth fundamental research 
belongs to the universities with heavy gov- 
ernmental subsidy, and that such an insti- 
tution no longer occupies a unique posi- 
tion in the national scene as it once did. 
When this view is based on more than a 
casual estimate of national trends, it usu- 
ally implies two criticisms: first, that the 
research institution is isolated and that the 
interchange and cross-fertilization of a 
university community is necessary for best 
progress in these days when disciplines are 
becoming more intimately interlinked; sec- 
ond, that fundamental research and the 
education of brilliant students should be 
closely related and that the research insti- 
tution is prone to become ingrowing and 
stodgy in the absence of the continual im- 
pact of young minds. 

These are cogent points, and the research 
institution that wishes to preserve its health 
had better pay attention to them. The 
problem of isolation is mitigated when re- 
search departments of an institution are 
located close to a university, as some of 
ours are. But isolation is more a matter of 
attitude than of geography. It is quite pos- 
sible for two departments of a university, 
in adjacent fields, to occupy the same 
group of buildings for years without a 
trace of genuine collaboration or mutual 
inspiration; such isolation is in fact ex- 
emplified all about us. On the other hand, 
a research department far from universities 
may become a national or even a world 
intellectual center in its field, the place 
where those intimate interchanges between 
masters occur which are often the seeds of 
progress. In biology Woods Hole has per- 



formed this function admirably; and in 
genetics Cold Spring Harbor is now a 
mecca, as are Mounts Wilson and Palomar 
in astronomy. Interchange, the antithesis 
of isolation, has its burdens and its abuses; 
too much of the wrong sort can be a 
nuisance. But the department or institu- 
tion which gives the appearance of being 
sufficient unto itself, which neither gives 
nor takes, which tries to crawl into a hole 
where it will be undisturbed in pursuit of 
its inclinations, is sick and in need of a 
radical operation. 

One should not make the error of re- 
garding formal education as the only 
means of contact with youth. Formal edu- 
cation is not the business of the research 
institution. But if a research institution 
allows itself to become old in its ways, the 
fault is its own. It can and must, if it is to 
maintain its vigor, expose itself constantly 
to the influence of young minds. Much de- 
pends on how they are selected and how 
they are treated. Contact with a group of 
graduate students in a university has its 
needling effect and its invigorating influ- 
ence; it also has its chores and involves 
duties to students of only average ability. 
The research institution, if it will, can se- 
lect the cream, not only in mental capacity 
but in the subtle characteristic of being 
able to fit well into a scientific community. 
Once selected, its younger staff members 
can be made genuine participants in its 
programs and in its group arguments and 
plans. Organization within a department, 
discipline of a sort, grades and titles, are 
of course necessary. But there should be 
no caste when a group of scientists meet 
for a scientific discussion, in twos or tens; 
and there should be no discrimination on 
account of age or reputation. The young- 
ster, in a gathering of two or fifty, should 
be given his opportunity on the floor by 
common consent, provided only that he 



REPORT OF THE PRESIDENT, 1953 



has something to say and knows how to 
say it briefly and to the point. And i£ he 
does not know how, he will soon learn, 
with encouragement and in the right at- 
mosphere, provided he has the stuff. 
Though the problem of inducing partici- 
pation on the part of younger members is 
not unique to the research institution, it 
is especially important to it; for the influ- 
ence of the presence of youth is hardly 
automatic in the institution's case, and 
the dangers of getting into grooves and 
of slipping into scientific fixity are greater 
in a community of scientists alone than 
in more diversified aggregations. 

These are the prime dangers of the in- 
dependent research institution. But they 
are more than offset by its advantages. 
The advantages could be enumerated and 
examined at length. But only two will be 
treated, two central points which are often 
misunderstood. 

It has long been realized that one of the 
most effective ways to ensure outstanding 
achievements in fundamental research is to 
locate the individual of genius and sup- 
port him liberally as he pursues his own 
way. This is indeed important, and An- 
drew Carnegie realized it fully, as is shown 
by the early records of the Carnegie Insti- 
tution of Washington. But there is more 
to it than the simple statement indicates, 
and the independent research institution 
is in a good position to refine and develop 
the simple idea to advantage. 

We need genius, of course. But there 
are geniuses who are utterly lone workers, 
who are lacking in generosity and unduly 
jealous of their reputations, who will re- 
tire into a cubicle and work with no man. 
Great things have been accomplished by 
such individuals in the past and will be 
in the future. But much more has been 
and will be accomplished by those who 
have brilliant creative skills combined with 



human attributes that make them always 
welcome in a community of their peers. 
Their full accomplishment may not ap- 
pear in their own papers, for they will be 
surrounded by devoted disciples, and their 
creative contribution will be in men as 
well as in direct results. The independent 
research institution furnishes an ideal cli- 
mate in which such individuals can func- 
tion to best advantage. Within it the pro- 
gram of each department, created by the 
staff itself, never handed down from above, 
is more than the sum of its parts. Each 
senior member formulates his own pro- 
gram, of course; but he does it in con- 
cert with his fellows, so that a depart- 
mental program emerges, interrelated, mu- 
tually contributory — a broad program for 
progress on which all can embark with 
enthusiasm. A university department can 
do this too; but it is more readily done 
by a research institution, free from the dis- 
tractions of teaching and the manifold set 
of relations that exists in a faculty. 

The other part of the problem of sup- 
porting genius is to find the genius before 
he has matured and made a reputation; 
for otherwise, changing his environment at 
best merely gives him a wider opportunity 
and at worst is a form of piracy. There are 
occasional leaders in science and learning 
equipped with a sixth sense who can do 
this well. Such a one was Daniel Coit 
Gilman, who, putting full time into the 
effort for a considerable period, assembled 
at Hopkins a brilliant congeries of schol- 
ars: Rowland, Welch, Osier, Gildersleeve, 
Remsen, Martin. But such gifted leaders 
are far more rare than the geniuses they 
seek. In fact it is doubtful whether genius 
is as rare an attribute as it is generally sup- 
posed to be, and whether there are not far 
more men who would blossom into great 
creativeness if given the chance. One 
means of attracting men to a university 



CARNEGIE INSTITUTION OF WASHINGTON 



faculty is the august committee of selec- 
tion, which passes on nominations and 
brings men of distinction in from the out- 
side. This means is not an effective one 
for finding the promising youth at the 
beginning of accomplishment, for commit- 
tees very seldom take risks. It can, more- 
over, be deadening to the morale of the 
youngsters struggling up inside the organi- 
zation. The best way to pick young men 
of promise is to have the selection done by 
a man in the same field, subject to checks. 
This is the way it is done in the Carnegie 
Institution of Washington. The person 
who makes the initial selection is the direc- 
tor of the department. His checks are 
of two sorts. First, his senior staff partici- 
pate with him, suggesting and judging; 
and one can be rather sure that if they wel- 
come a youngster with practical unanimity 
he will fit, even though to a casual lay 
observer he might seem to be rather a 
queer specimen of the race. The other 
check is by the President and Trustees, 
who, though they can hardly compare indi- 
viduals in detail, can certainly ascertain 
that standards are held high and adequate 
diligence is employed in the search. The 
best way to get a new young scientist of 
great creative ability into a group is to have 
a group that is made up to a considerable 
extent of men of just that character, and 
then allow them to select their novices, 
with provision for rotation and further 
selection — all under the leadership of a 
scientist with judgment. Judgment in the 
selection of men is, in fact, one of the 
primary attributes of a successful director 
of research. Again, all this can be done 
in a university department. But the tightly 
knit group in a research institution can 
do it better. 

There are many things which a univer- 
sity can do better than a research institu- 
tion. But this is a discussion of funda- 



mental research. In this field the research 
institution is paramount and is by no 
means an obsolescent form of organiza- 
tion. It can, if it will, carry on funda- 
mental research in a most fruitful way, 
better on the whole than can be done any- 
where else. So there is a place for it in the 
future if conditions are such as to allow it 
to prosper. 

The principal condition, though not the 
only one, for ensuring the prosperity of re- 
search institutions is financial. It is, more- 
over, a matter of endowments rather than 
of current funds for projects. 

There have been important trends in 
the financing of research in this country. 
Since 1920, according to a recent report by 
C. I. Campbell, the fraction of the total 
national income devoted to research has 
been multiplied by ten. But the fraction 
devoted to fundamental research has in- 
creased relatively little. The federal gov- 
ernment has entered strongly into sup- 
port of research, but its entrance has 
brought a host of problems, and its sup- 
port is largely confined to projects, some of 
them in basic research. These projects al- 
low an organization such as a university 
to expand its operations. But they do not 
create new centers of research, nor do they 
allow old ones to proceed to a permanently 
secure basis of larger effort. The Car- 
negie Institution of Washington has not 
participated in government contracts, ex- 
cept in the case of a few projects where 
there seemed to be a duty to do a tem- 
porary piece of work. It has not felt that 
enlargement on the basis of such contracts 
would be entirely healthy, and it is strongly 
inclined to retain its complete independ- 
ence. Although the federal program has 
been an aid to many a college or uni- 
versity in time of difficulty, it has its 
dangers, and participation should be cir- 
cumspect. 



REPORT OF THE PRESIDENT, 1953 



The great foundations have turned away 
from endowment grants, and the new 
foundations that are formed do not enter 
this field. There are many reasons for 
this. One valid reason is that giving away 
money in great sums transfers the respon- 
sibility for its use to others, and a founda- 
tion often prefers to do its own thinking, 
beyond the mere selection of a few institu- 
tions from among many to receive its 
largess for the furtherance of their sev- 
eral purposes. This change in the policy 
of foundations, however, adds to the great 
sums being spent on a project basis. And 
the temporary project is not a sound way 
in which to carry on fundamental studies 
of depth or subtlety. 

The project idea, introduced largely dur- 
ing the war and as a necessity at that time, 
is far better adapted to applied research 
than to fundamental research. This is part 
of the reason why fundamental research 
has not been expanded to the extent that 
it should be. The foundations here have 
to some extent missed an opportunity. As 
the government entered strongly into sci- 
entific research, they moved out. If they 
had moved into basic research, they might 
have preserved a balance. There was 
plenty of opportunity for them to exercise 
their talents of review and analysis in seek- 
ing areas of opportunity, for the scope of 
fundamental research has expanded far 
more than the means for its furtherance. 
There was hence opportunity to create 
new institutions, endowed and independ- 
ent, where they were most likely to pros- 
per. A bit of this has been done; and there 
are exceptions to the comments above, of 



course. Carnegie Corporation donated five 
million dollars for endowment to the Car- 
negie Institution of Washington when it 
was sorely needed. But in general the 
foundations have not tackled the problem 
of extending fundamental scientific re- 
search in this country, nor is there any 
great indication that they will do so. 

New independent research institutions 
have been established by individual philan- 
thropists — the day of great fortunes and of 
great altruism accompanying them is not 
over. Yet these have been largely directed 
at specific objectives, often in the medical 
field, and often of a semi-applied nature. 
This is not because men of wealth lack 
interest in search for the unknown or ap- 
preciation of the value, spiritual or aes- 
thetic if you will, of the search for under- 
standing, unencumbered by more imme- 
diate objectives. It is rather that such men 
understand better the sufferings and needs 
of humanity and are anxious to alleviate 
them. 

This may be a reflection of our cultural 
immaturity. As we proceed, there may be 
more among us, highly successful in af- 
fairs, anxious to serve humanity, who will 
wish to look at the stars, or delve into the 
earth, or probe for the secret of life, not 
because it will add to the comforts or re- 
duce the hazards of existence, but because 
it may render us a more dignified and un- 
derstanding race with greater satisfaction 
in living. If so, there will be more and 
greater independent research institutions 
devoted to the search for knowledge for 
its own sake. 



Research Activities 

The reports of the Directors of the De- At the Mount Wilson and Palomar Ob- 

partments of Research may be read in de- servatories, H. D. and H. W. Babcock, 

tail in the Year Boo\. I shall summarize taking advantage of the greatly increased 

only a few highlights here. resolving power of the new Mount Wilson 



CARNEGIE INSTITUTION OF WASHINGTON 

gratings, and of new photoelectric tube nebula, using cepheid variables as distance 
techniques that have become available indicators. He then proceeded to derive 
since the war, have recently made an en- the distances of various other nebulae and 
tirely new approach to the problem of the groups of nebulae extending out to the 
general magnetic field of the sun. Their extreme range of the ioo-inch telescope, 
new equipment permits them to make by referring them to the distance of the 
automatically twenty to thirty uniformly Andromeda nebula as a standard. These 
spaced traces across the sun's surface, re- very fundamental studies extended the 
cording with greatly increased accuracy the diameter of the measured universe many 
value of the magnetic intensity and po- thousandfold and revolutionized our ideas 
larity for each point covered. The sun's as to the extent of the universe, 
surface has been scanned in this way on But like all first measurements made at 
most of the clear days for the past year, the extreme range of available equipment, 
The new observations confirm the exist- these early results were very rough and 
ence of a general magnetic field, much were subject to certain assumptions as to 
weaker than earlier measurements sug- the properties of the distance indicators 
gested, and limited to the neighborhood used. One of the first programs, therefore, 
of the poles. Stronger fields, more local- planned by the nebular department for the 
ized and transient, are also occasionally new Hale telescope was a step-by-step re- 
found in the spot-free areas at lower lati- study of the problem of the distance scale, 
tudes. These changing fields seem to af- This included a repetition of all measure- 
ford an explanation for the occasional ments with the higher precision made pos- 
large and erratic values of the earlier re- sible by the Hale telescope and by more 
suits, which by the very laboriousness of advanced techniques now available. It also 
the measurements were limited to a few involved a re-examination of the proper- 
isolated points on the sun's surface. ties of the distance indicators used, in the 

The new techniques clearly open up for light of recent discoveries concerning the 

study the whole subject of magnetic fields various stellar populations of the near-by 

and their fluctuations with time over the nebulae such as the Andromeda. Though 

sun's surface. They also indicate the de- final results for all the steps are not yet 

sirability of continuing daily scans of the completed, the preliminary values obtained 

sun's surface for some time, preferably for by Walter Baade and his collaborators in- 

the next sunspot cycle or two, in order to dicate that a drastic revision of the dis- 

find what connections, if any, exist be- tance of the Andromeda nebula and other 

tween these magnetic fields and other solar distances dependent on it will be required, 

phenomena. Thus these tentative results lead to the 

Very significant contributions have also conclusion that the earlier values of the 
been made during the current year to an- distances and linear dimensions of all 
other major problem that has been under nebulae must be approximately doubled 
attack at the Observatories for the past and of their luminosities quadrupled. Fur- 
quarter century. This is the problem of thermore, the old values of the nebular 
the scale of the observable universe. masses, as determined from the linear di- 

Edwin P. Hubble in the late 1920's sue- mensions and the relative radial velocities 

ceeded in making the first definite meas- of the nucleus and periphery of the nebu- 

urement of the distance of the Andromeda lae, must be doubled. Moreover, if we 

8 



REPORT OF THE PRESIDENT, 1953 

assume the reality of the expanding uni- salts, the solubility in water drops off al- 

verse, the age of the universe since the most to zero at the critical temperature of 

expansion started from a common origin water. If the temperature is raised a small 

must be doubled. amount above the critical point, but the 

During the past year a new and ex- pressure is also enormously increased, solu- 

tremely sensitive light-measuring device in bility again becomes measurable; and in 

the form of a photon counter has been some cases, the gases have been able to 

developed by William A. Baum for the dissolve more than their own weight of 

Hale telescope. The new device makes it inorganic salt. Most of the work with 

possible to measure the light received from volatiles has been done with water, but 

an object at the extreme limit that can be it has been found that the inclusion of 

photographed with the 200-inch telescope, small proportions of other gases may pro- 

This limit was found to be at magnitude duce profound effects on the solubilities of 

23, which indicates that the Hale telescope solids in hot, highly compressed gases and 

has already reached objects considerably gaseous mixtures. 

fainter than had been expected when the Bacterial cells can be conceived of as 

telescope was planned. chemical processing plants wherein the 

The experimental difficulties that have raw material from the culture fluid is 
hampered work at the Geophysical Lab- utilized to provide the substance and en- 
oratory with rock-forming minerals mixed ergy needed for the synthesis of a variety 
with volatile components, chiefly water, of products. As a first step, the raw mate- 
have now been surmounted by improved rial is converted to a group of intermedi- 
techniques devised by George W. Morey, ates which are then used for further syn- 
O. Frank Tuttle, and H. S. Yoder. The thesis. Simultaneously, a part of the raw 
studies of these men are giving us a better material is oxidized to provide energy, 
understanding of the formation processes These operations are nicely balanced to 
of granite, the most common rock on the provide the proper supply of each inter- 
surface of the earth. They have given us mediate. Experiments carried out during 
a new insight into the chemistry of the the past three years at the Department of 
ubiquitous micas, found in all rock types — Terrestrial Magnetism have given some 
igneous, metamorphic, and sedimentary, insight into the kinetic chemical aspects of 
They are yielding information pertinent growing bacterial cells. By measuring the 
to geological problems ranging from vol- incorporation of a variety of isotopically 
canism to metamorphism and the second- labeled compounds it has been possible to 
ary enrichment of ore deposits. They are determine the rates of flow in many of 
also opening up a new field of study in the reaction sequences of the cell. These 
inorganic chemistry. Apparatus is now in flow patterns account for more than 80 
current use which can give pressures up per cent of all the carbon incorporated, 
to 200,000 pounds per square inch, at which is converted from glucose to the 
temperatures of 1000 C or higher, and amino acids, purines, and pyrimidines sub- 
studies with such apparatus have empha- sequently used as building blocks for the 
sized that the solubility of solid inorganic synthesis of the giant molecules of protein 
substances in compressed gases can reach and nucleic acid. 

unexpected magnitudes. With silica and The flow in the Krebs cycle was studied 

most minerals and with many inorganic with particular attention. This cycle has 



CARNEGIE INSTITUTION OF WASHINGTON 

long been recognized in mammalian tissue, the wind motions which produce them are 
where its chief function is oxidation. The initiated by radiations and perhaps by par- 
present studies show that in Escherichia tides from the sun. 

coli growing with glucose as the sole car- The biochemical group of the Depart- 
bon source, the Krebs cycle acts chiefly to ment of Plant Biology has been investigat- 
synthesize aspartic acid and glutamic acid, ing the nature and function of the pig- 
These amino acids are used in part directly ments by which the influences of light on 
in protein synthesis and in part as inter- plants are mediated. As a key to the par- 
mediates in the production of seven other ticipation of pigments in the photosyn- 
amino acids, and thus supply more than thetic process, an effect of light on the 
50 per cent of the carbon required for pigments during photosynthesis has often 
protein. In this case the Krebs cycle is of been looked for. Such an effect was first 
major importance in synthesis but con- discovered by L. N. M. Duysens, working 
tributes little to oxidation. A similar situa- at Utrecht. He found reversible changes 
tion has been found in an alga {Chlorella in the absorption spectrum of the particu- 
pyrenoidosa), a. yeast (Torulopsis utilis), lar kind of chlorophyll that occurs in cer- 
and a mold (Neurospora crassa). tain photosynthetic bacteria, which show 

The flows in the Krebs cycle and in that the chlorophyll itself undergoes chemi- 

other synthetic reactions are not rigidly cal changes induced by light. This year, 

fixed. On the contrary, they are responsive as a Fellow of the Institution, he has found 

to the conditioning of the culture medium, that these changes are increased when 

Under certain circumstances the flow of oxidizing substances are added to the bac- 

the Krebs cycle alters to emphasize oxida- teria and decreased in the presence of sub- 

tion rather than synthesis. Two types of stances, such as peptone, that enter into 

response to changing conditions have been the normal metabolism of the cells. This 

studied in E. coli, an immediate change in shows a close connection between the cellu- 

the flow rates due to a change in the chemi- lar metabolism and the pigments, and 

cal environment, and a slower adaptive bears directly on one of the major prob- 

change wherein the flow rates are further lems in photosynthesis, namely, how the 

altered by changes in the enzymatic con- pigments are coupled to the enzyme sys- 

stitution. This flexibility in the cell's re- terns. 

sponse allows it to survive and prosper in a Leaves grown in the dark have a pig- 
wide range of environmental conditions, ment, protochlorophyll, which changes to 

New evidence has unexpectedly devel- the photosynthetic pigment, chlorophyll, 
oped of the importance of atmospheric cir- by the absorption of light. James H. C. 
culation and zonal winds in the produc- Smith and Allen Benitez have found that 
tion of magnetic storms. The further elab- this change is remarkable in that it occurs 
oration of the dynamo theory, made pos- in leaves far below their freezing point — 
sible by modern studies of winds in the even at the temperature of —77° C. The 
upper atmosphere coupled with recent rate of this change and its extent diminish 
revisions in our understanding of the elec- as the temperature is lowered below the 
trical conductivity of the ionosphere over- freezing point of water. The behavior at 
head, now indicates that the electric cur- low temperatures suggests that two mole- 
rents which produce magnetic storm effects cules of protochlorophyll, one of which is 
are primarily in the atmosphere, and light-activated, interact to form chloro- 

10 



REPORT OF THE PRESIDENT, 1953 

phyll. Glycerine extracts of protochloro- has been shown that this nucleic acid has 
phyll from leaves have been prepared that the composition of the nucleic acid found 
also show this light-activated transforma- in the infecting phage and that it is, in 
tion. This glycerine-extracted protochloro- fact, a precursor of phage particles formed 
phyll changes in the dark to another form later on. These findings are consistent 
of protochlorophyll with a different color, with genetic results suggesting an intra- 
This finding is significant because it has cellular population of multiplying non- 
clarified the puzzling discrepancy between infective phage and with the idea that the 
the previously measured action and fluores- noninfective phage particles consist of or 
cence spectra of protochlorophyll in leaves, contain nucleic acid. 

The influence of light on the consistency Studying the mechanism of genetic 
of protoplasm in plant cells, which has changes, with maize as an experimental 
been shown in water plants, has this year material, Barbara McClintock of the De- 
been found by Hemming Virgin to occur partment of Genetics has found that the 
in several land plants. Measurements of presence of a mutation-inducing factor at 
the relative effectiveness of different colors a particular locus in a maize chromosome 
of light on the phenomenon demonstrated has resulted in the production of a large 
that only blue and blue-green light have number of mutations affecting the action 
the effect of changing the viscosity of the of genes to either side of it. Some of the 
cytoplasm of terrestrial plants. mutation-inducing events affect only the 

One of the most important properties of action of an immediately adjacent gene, 
living organisms is their capacity to repro- Others alter the action not only of this 
duce; and one of the greatest puzzles of gene, but also of those located beyond it. 
science is the question of how reproduction Thus a single mutation-inducing event, 
is accomplished, in terms of chemical and occurring at one particular locus in a chro- 
biological processes. A. D. Hershey, of the mosome, can result in the spread of muta- 
Department of Genetics, has been studying tional change along the chromosome. In 
reproduction in bacteriophages. His earlier the case studied, the spread included a re- 
work suggested the possibility that infec- gion known to be at least six crossover 
tion of the bacterium Escherichia coli by units in length. Spread beyond this limit 
bacteriophage T2 starts off by injection of could not be determined because of the 
pure phage nucleic acid into the cell. This inclusion of genes whose altered action 
possibility has now been partially con- had an adverse effect on viability, 
firmed in the following ways: (1) So far The work of the Department of Embry- 
it does not appear that any labeled amino ology during the year has pursued its cen- 
acids present in the parental phage parti- tral aim of working out the development 
cles are transferred to offspring particles, of function in relation to the development 
(2) Chemical analysis of isolated phage of bodily structure in the embryo and fetus, 
does not reveal any basic protein (usually Among the noteworthy advances is a study 
associated with nucleic acid in chromo- by S. R. M. Reynolds and associates at 
somes), or any protein other than the Oxford of the action of the blood circula- 
coat material, which is metabolically in- tion, especially of the lungs of the new- 
active during phage growth. (3) Rapid born animal just before and after the time 
synthesis of nucleic acid begins immedi- of its birth. Before respiration begins the 
ately after infection of a bacterial cell. It lungs require only a small amount of cir- 

II 



CARNEGIE INSTITUTION OF WASHINGTON 

culating blood, sufficient to care for nour- in the uterus, it gives concrete evidence 

ishment of the developing but as yet un- that human single-ovum twinning actually 

used living tissue. Immediately after the does occur in at least one of the several 

first expansion of the lungs after breath- ways that have been postulated on theo- 

ing begins, large amounts of blood are re- retical grounds — in this case by the devel- 

quired to provide for the respiratory ex- opment of the fertilized egg cell into a 

change of oxygen and carbon dioxide for single blastocyst (hollow spherical stage), 

the whole body. The sudden filling of the within which the inner cell mass, usually 

lung vessels with blood is associated with single, divided into two separate embry- 

extreme changes in blood pressure in the onic areas. 

heart chambers and great vessels, and sets During the past season the Department 

up conditions which are critical for the of Archaeology began large-scale excava- 

infant. Full understanding of these changes tions at the ancient city of Mayapan, which 

is necessary not only for physiological is now the center of the Department's 

study, but also for enabling obstetricians to activities. The materials and raw data 

deal effectively with emergency circulatory emerging from this work seem to indicate 

stresses in the newborn infant. that some profound changes occurred in 

The intensive investigation of the physi- the local culture during the late stage of 

ology of uterine muscle by Arpad Csapo Maya civilization represented by the ar- 

has been continued with the collaboration chaeological remains at Mayapan. For ex- 

of Beni Horvath and Brenda M. Schofield, ample, the numerous fragments of effigy 

and from it much has been learned about incense burners of pottery, apparently 

the action of the ovarian hormones. Little household idols, in the shrine room of an 

has been known about the precise way in excavated dwelling suggest a decline in the 

which these "chemical messengers" affect importance of the old priestly and public 

their target organs. The work on uterine religion and a turning to private religious 

muscle has taken a step forward by reveal- practices carried on in the home. The de- 

ing that progesterone, one of the ovarian cline in importance of old religious forms 

hormones, produces its effects on muscle is further suggested by what may have 

tissue by altering the rate of access of been a late encroachment of dwellings 

potassium ions to the contractile tissue. into the ceremonial areas of the city. 

The collection of early human embryos These are interpretations that must be sup- 
at the Department of Embryology received ported by other evidence before much 
a notable addition from Chester H. Heu- weight is given to them, but it is worth 
ser, Research Associate, namely the earliest noting that the changes in religious prac- 
known human twin embryos, of about tices indicated by the archaeological evi- 
seventeen days' development. Because the dence seem to be confirmed by the Span- 
specimen is complete, consisting of the ish descriptions of Maya culture at the 
two embryos and intact membranes in situ time of the Spanish Conquest. 

Staff 

It is always pleasant to call to your at- Wilson and Palomar Observatories, was 

tention the honors that have come to direc- awarded the Ives Medal of the Optical 

tors and staff members of the Institution. Society of America, received the degree of 

Ira S. Bowen, Director of the Mount Doctor of Science honoris causa from 

12 



REPORT OF THE PRESIDENT, 1953 



Princeton University, and was elected Cor- 
responding Member of the Royal Society 
of Sciences at Liege. By invitation Walter 
Baade, staff member of the Observatories, 
spent May and June 1953 at Leiden Uni- 
versity and at Groningen University, Hol- 
land. Dr. Baade was elected a member of 
the American Philosophical Society; a 
Foreign Member of the Royal Netherlands 
Academy of Sciences; and President of 
Commission 28 (Extragalactic Nebulae) 
of the International Astronomical Union. 
The National Science Foundation named 
him as Principal Scientist at a Symposium 
on Astrophysics held at the University of 
Michigan in June and July 1953. Edwin P. 
Hubble gave by invitation the Darwin Lec- 
ture of the Royal Astronomical Society 
and the Cormack Lecture of the Royal 
Society of Edinburgh. Jesse Greenstein 
was elected President of Commission 29 
(Stellar Spectra) of the International Astro- 
nomical Union and was appointed Chair- 
man of a panel of consultants in astron- 
omy, advisory to the National Science 
Foundation. Harold D. Babcock, retired 
staff member, was awarded the Bruce 
Medal of the Astronomical Society of the 
Pacific. 

J. Frank Schairer, physical chemist at the 
Geophysical Laboratory, was elected to the 
National Academy of Sciences on April 
29, 1953. The Volcanology Section of the 
American Geophysical Union re-elected 
Dr. Felix Chayes as its Secretary for a 
three-year term. 

At the Department of Terrestrial Mag- 
netism, Merle A. Tuve, Director, was in- 
vited to serve for a two-year term on the 
Visiting Committee of the Department of 
Geology of Massachusetts Institute of 
Technology. On May 11, 1953, he received 
the degree of Doctor of Science honoris 
causa from the University of Alaska for 
fundamental research contributions to stud- 



ies of the upper atmosphere and for his 
distinguished service over the years in con- 
nection with the Geophysical Institute of 
the University. Harry W. Wells, a staff 
member of the Department, was made a 
Fellow of the Institute of Radio Engineers 
on November 6, 1952, "in recognition of 
his contributions to ionospheric research 
and the organization of a world-wide net- 
work of ionospheric stations." 

M. Demerec, Director of the Depart- 
ment of Genetics, presented a paper at the 
Symposium on Evolution organized by the 
Society for Experimental Biology and the 
Genetical Society of Great Britain, held at 
Oxford, England, in July 1952. In the same 
month Alfred D. Hershey, microbiologist 
of the Department, participated in a Sym- 
posium on Immunochemistry at the meet- 
ing of the Society of Biological Chemists 
in Paris. 

George W. Corner, Director of the De- 
partment of Embryology, spent the year 
at Oxford, England, where he was George 
Eastman Visiting Professor in the Uni- 
versity of Oxford and Fellow of Balliol 
College. While in England he gave the 
Ciba Foundation Lecture in London on 
December 4, 1952. During his absence he 
was elected Vice President of the National 
Academy of Sciences on April 29, 1953. 
Robert K. Burns, staff member of the De- 
partment, received the degree of Doctor 
of Science honoris causa from his alma 
mater, Bridgewater College, Bridgewater, 
Virginia. 

The Peabody Museum, Harvard Uni- 
versity, appointed H. E. D. Pollock, Direc- 
tor of the Department of Archaeology, a 
Research Fellow in Middle American Ar- 
chaeology. While attending a meeting of 
the 30th International Congress of Ameri- 
canists in Cambridge, England, in August 
1952, J. Eric S. Thompson, staff member 



*3 



CARNEGIE INSTITUTION OF WASHINGTON 



of the Department, was elected President 
of the Congress. 

Elias A. Lowe, Research Associate of the 
Institution, with the Institute for Ad- 
vanced Study, was elected an Honorary 
Fellow of Corpus Christi College of Ox- 
ford University, England. 

Two members of the scientific staff of 
the Institution have retired. 

Paul W. Merrill, who has been associ- 
ated with the Mount Wilson Observatory 
since January i, 1919, retired on Septem- 
ber 1, 1952. He served as editor of the 
Observatory publications from 1939 until 
his retirement, and from 1949 until his re- 
tirement he was a member of the Observa- 
tory Committee of the Mount Wilson and 
Palomar Observatories. Dr. Merrill's field 
of research is stellar spectroscopy with spe- 
cial emphasis on long-period variable stars. 
His book Spectra of Long-Period Variables, 
which appeared in 1940, is a classic in its 
special field. An earlier work, The Nature 
of Variable Stars, issued in 1938, is particu- 
larly enlightening to the layman. Dr. Mer- 
rill is one of the foremost authorities on 
spectrum analysis. His outstanding con- 
tributions in the field of astronomy were 
recognized by his election to the National 
Academy of Sciences in 1929 and by the 
Academy's award to him of the Draper 
Medal in 1946 "for his many important 
contributions to astronomical physics, in 
particular, those relating to his researches 
in stellar spectroscopy." The same year 
he was presented the Catherine Wolfe 
Bruce Gold Medal by the Astronomical 
Society of the Pacific. One of Dr. Merrill's 
recent contributions was a report to the 
National Academy of Sciences on the dis- 
covery that the element technetium, origi- 
nally found in nuclear experiments, exists 
in stars of type S, although it has not been 
found to exist naturally on the earth. 



Dr. Merrill is continuing his researches 
and writing. 

E. Carleton MacDowell, staff member 
of the Department of Genetics, retired on 
October 1, 1952, after thirty-eight years of 
service. His early studies of the effects of 
alcohol on reproduction and sex ratio in 
mice stimulated his interest in studies of 
growth. In 1928 Dr. MacDowell began his 
pioneer investigations of leukemia, and 
since that time he has carried on an inten- 
sive research program dealing with basic 
problems of leukemia. His work in this 
field in collaboration with associates at 
Cold Spring Harbor and pathologists and 
physiologists elsewhere established that leu- 
kemia is a malignant growth comparable 
to cancer, and that, like cancer, it can be 
transmitted from one individual to an- 
other by transplantation of affected cells. 
Many lines of leukemia, characterized by 
specific differences, were isolated. Cross- 
ing experiments showed simple Mendelian 
segregation of resistance and susceptibility, 
indicating that one important recessive 
gene is responsible for the resistance. It 
was also found that the transmission of 
resistance depends partly on the age of 
either the nurse or the mother. One of 
the latest achievements of MacDowell's 
group was the isolation from the leukemic 
cells of an X factor which apparently has 
the effect of inducing resistance to certain 
transplanted leukemias. Dr. MacDowell is 
continuing his research on the mechanism 
that induces resistance to line-I leukemia 
with Dr. J. Victor, of Camp Detrick, 
Maryland, under a grant to the Biological 
Laboratory of the Long Island Biological 
Association. 

With the deepest regret I must record in 
this year's review the deaths of three of 
the Institution's retired staff members and 
one member of the active staff. 

George R. Wieland, internationally 






H 



REPORT OF THE PRESIDENT, 1953 

known paleobotanist, who retired on Feb- urements of optical properties of grains 

ruary i, 1933, died on January 18, 1953, in only 0.01 mm in size could be quickly and 

his eighty-seventh year. The Institution conveniently carried out; his contribution 

supported his studies on living and fossil during World War I to the development 

cycads from 1903 until 1941. He became and manufacture of optical glass; and his 

a Research Associate in 1907 and in 1917 special studies as Chairman of the Com- 

was made an Associate in Paleontology, mittee on the Study of the Surface Fea- 

Wieland was also a member of the Yale tures of the Moon, which he carried on 

University faculty from 1906 until 1935. from 1924 until 1939 at the Mount Wilson 

He discovered the petrified forest of cycads Observatory. His outstanding work in the 

in the Black Hills of South Dakota and field of minerals was recognized by the 

was the founder and donor of the Fossil Mineralogical Society of America when it 

Cycad National Monument there. presented him with the Roebling Medal 

George R. Wait, retired staff member on November 14, 1952. 
of the Department of Terrestrial Magnet- The sudden death of Edwin P. Hubble, 
ism, died on April 9, 1953, at the age of staff member of the Mount Wilson and 
66. He played an important part in the Palomar Observatories, on September 28, 
discovery of the world-wide simultaneous i953> cut short one of the most fruitful 
pattern of daily variation in the earth's elec- careers in the field of astronomy. Hubble 
trie field. His studies of atmospheric ioni- joined the staff at Mount Wilson on Sep- 
zation and the origin and maintenance of tember 1, 1919, and served continuously 
the earth's electric charge furnished strong except for a period during World War II 
support to the theory that thunderstorms from 1942 to 1945, when he was Chief of 
of the globe are responsible for the steady the Exterior Ballistics Branch, Army Ord- 
negative electric charge of the earth with nance Ballistics Research Laboratory at 
respect to the upper atmosphere and iono- Aberdeen Proving Ground, Maryland. His 
sphere. early observations with the 100-inch tele- 
Fred E. Wright, retired staff member of scope on Mount Wilson revolutionized the 
the Geophysical Laboratory, died suddenly ideas of astronomers regarding the mag- 
at his summer home in Canada on August nitude of the universe. Before 1920 the 
25, 1953. Since his retirement on Novem- universe was conceived of as one great 
ber 1, 1944, he had occupied an office in stellar system, the Milky Way; but Hub- 
the Administration Building, where he ble's studies showed that our Milky Way 
worked on a revision of his authoritative system is only one of some hundreds of 
Methods of Petrographic-Microscopic Re- millions of such stellar systems extending 
search: Their Accuracy and Range of Ap- out to the extreme limit of observation 
plication, which the Institution first pub- through our largest telescopes. His subse- 
lished in 191 1. For nearly half a century quent measurements of the radial velocities 
Wright was a leader in the development of of extragalactic nebulae led to the signifi- 
methods for the identification of minerals cant conclusion that they were receding 
by the petrographic microscope. He joined from us and that those farthest away were 
the staff of the Geophysical Laboratory on moving faster than those that were nearer. 
January 1, 1906, and brought great distinc- These observations were the basis of the 
tion to the Laboratory through his perfec- now widely held theory of the expanding 
tion of techniques whereby accurate meas- universe. Hubble's discoveries emphasized 

'5 



CARNEGIE INSTITUTION OF WASHINGTON 



the need of greater telescopes and provided 
one of the chief reasons for the construc- 
tion of the 200-inch Hale telescope on 
Palomar Mountain. He assisted in the de- 
signing of this instrument and carried out 
the first observations with it. He served on 
the Observatory Committee from the start 
of the joint operation of the Mount Wil- 
son and Palomar Observatories in 1948, 
and his counsel in the operation of the 



Observatories was highly valued. Hub- 
ble's scientific eminence was widely recog- 
nized. He received honorary degrees from 
several of the great universities both in 
the United States and abroad; he was 
awarded a number of gold medals for his 
achievements in the field of astronomy, 
and was elected to honorary membership 
in some of the most distinguished learned 
societies. 



Finances 



During the fiscal year ended June 30, 
1953, income from investments, exclusive 
of stock dividends, amounted to $1,917,- 
288.10, an increase of $28,718.52 over the 
previous year. The yield at book value of 
securities held during the year was 4.36 per 
cent, and at market value on June 30, 1953, 
the yield was 3.79 per cent. Appropria- 
tions authorized by the Board of Trustees 
for the fiscal year amounted to $1,828,- 
552.00, and additional funds transferred 
from the General Contingent Fund during 
the year by the Executive Committee 
amounted to $84,500.00, making the total 
amount of funds authorized during the 
year $1,913,052.00. 

The proportion of the Institution's port- 
folio invested in common stocks at the 
close of the year, at market, was slightly 
lower than a year ago. Common stocks 
held at June 30, 1953 represented 44.3 per 
cent of the portfolio, bonds 47.8 per cent, 
preferred stocks 7.3 per cent, and cash 0.6 
per cent, as compared with 49.2 per cent in 
common stocks, 42.8 per cent in bonds, 7.8 
per cent in preferred stocks, and 0.2 per 
cent in cash a year ago. The book value 
of securities held at the close of the fiscal 
year was $44,443,264.93, an increase of 



$1,052,891.21 over the previous year; and 
the market value of the securities was 
$50,224,304.00 as compared with a market 
value of $52,546,226.00 a year ago. 

Of the Institution's income from invest- 
ments, 60.9 per cent came from common 
stocks, 30.4 per cent came from bonds, and 
8.7 per cent from preferred stocks, an in- 
crease of approximately 3 per cent in the 
proportion of total income received from 
bonds, and a corresponding decrease from 
common and preferred stocks, over the 
previous year. 

It has been possible for the Institution 
to carry on its operations during the fiscal 
year within its available income without 
curtailment of any part of its major pro- 
gram. Also, some adjustments have been 
possible where necessary to relieve eco- 
nomic pressures. The Institution's re- 
serves have increased modestly and re- 
main in a healthy condition. 

Statements showing the financial posi- 
tion of the Institution at June 30, 1953, to- 
gether with a certificate of Haskins & 
Sells, Certified Public Accountants, appear 
with the report of the Executive Com- 
mittee. 



Trustees 

The Institution has suffered an uncom- tees: Frederic A. Delano, Homer L. Fer- 
mon loss in the death of three of its Trus- guson, and Lewis H. Weed. 

16 



REPORT OF THE PRESIDENT, 1953 

Frederic A. Delano, a Trustee of the 1953, in his eightieth year. He was elected 

Institution for twenty-two years, died in to the Board on December 9, 1927, and 

Washington on March 28, 1953, at the age resigned on September 8, 1952, owing to 

of eighty-nine. He was elected to the ill health. A member of the Auditing 

Board on December 9, 1927, and served Committee from 1931 to 1939 and again 

later as member and Chairman of the from 1945 to 1952, and a member of the 

Auditing Committee, Secretary of the Committee on Terrestrial Sciences from 

Board, and member of the Executive Com- 1939 to 1952, he always took an intelligent 

mittee, as well as member of the Commit- interest in the problems of the Institution, 

tees on Terrestrial and Biological Sciences, and his resignation from the Board was 

His resourceful counsel and his prevailing accepted with regret, 

keen interest in the affairs of the Institu- Ferguson's name was familiar to ship- 

tion were severely missed when he re- builders all over the world. After gradua- 

signed from the Board on October 13, 1949. tion from the Naval Academy in 1892 he 

A prominent and effective leader in the studied naval architecture at the University 

movement for rational city, state, and re- of Glasgow. The Newport News Ship- 

gional planning, Mr. Delano contributed building and Dry Dock Company, of 

much to the redevelopment of Chicago and which he was first superintendent of hull 

New York; and as Chairman of the Na- construction and later general manager, 

tional Capital Park and Planning Commis- president, and chairman of the board, is 

sion from 1926 to 1942 he was largely re- world famous for its merchant and naval 

sponsible for such improvements in the vessels. Under Ferguson's direction the 

Washington area as the revival of the company built fifteen of the Navy's big 

L'Enfant plan, the Mount Vernon Me- aircraft carriers including the Hornet and 

morial Highway, and the George Wash- Midway, fourteen battleships, and other 

ington Memorial Parkway. Navy vessels. 

He was valued as a public servant by Lewis H. Weed died on December 21, 

five presidents — Taft, Wilson, Coolidge, 1952, in Reading, Pennsylvania, at the age 

Roosevelt, and Truman — serving in the of sixty-six. He served on the Executive 

widely diverse capacities of member of the Committee from the time of his election 

Commission of Industrial Relations, mem- to the Board of Trustees on December 13, 

ber of the Federal Reserve Board, Colonel 1935- He was also appointed Chairman of 

in the Army in World War I as head of the Committee on Biological Sciences in 

Army transportation in Paris, Chairman 1937; and on March 19, 1947, he became 

of the League of Nations International Acting Secretary of the Board until his 

Committee on the production of opium in election as Secretary on December 12, 1947. 

Persia, and Chairman of the National Re- Dr. Weed was most generous in the time 

sources Planning Board. he gave to Institution problems, and his 

He will be remembered with deep af- sound judgment in their solution was al- 

fection by all who knew him and par- ways highly valued. His death leaves a 

ticularly by the staff in the Administra- gap which it will be difficult to fill, 

tion Building of the Institution, where he Within the relatively short span of his 

made his headquarters during the later life, Dr. Weed rendered distinguished 

years of his active life. service in the administration of medical 

Homer L. Ferguson died on March 14, research. After serving as professor of 

17 



CARNEGIE INSTITUTION OF WASHINGTON 



anatomy at Johns Hopkins University, he 
became Dean of the Johns Hopkins Medi- 
cal Faculty and Director of its School of 
Medicine. In 1939 he was appointed Chair- 
man of the Division of Medical Sciences 
of the National Research Council, and 
during World War II he also served as Vice 
Chairman of the Committee on Medical 



Research of the Office of Scientific Re- 
search and Development. He was espe- 
cially interested in the development of 
medical and other scientific libraries and 
was mainly responsible for the establish- 
ment of the Welch Library at Johns Hop- 
kins. 

Vannevar Bush 



18 



REPORTS OF DEPARTMENTAL ACTIVITIES 
AND CO-OPERATIVE STUDIES 

ASTRONOMY 

Mount Wilson and Palomar Observatories 

TERRESTRIAL SCIENCES 

Geophysical Laboratory 
Department of Terrestrial Magnetism 

BIOLOGICAL SCIENCES 

Department of Plant Biology 

Department of Embryology 

Department of Genetics 

ARCHAEOLOGY 

Department of Archaeology 

REPORTS OF RESEARCH ASSOCIATES 



MOUNT WILSON AND PALOMAR OBSERVATORIES 

Operated by the Carnegie Institution of Washington 
and the California Institute of Technology 

Pasadena, California 
IRA S. BOWEN, Director 

Observatory Committee 

Ira S. Bowen, Chairman Jesse L. Greenstein 

Horace W. Babcock Edwin P. Hubble 

Robert F. Bacher Ernest C. Watson 

The basic parts of the 200-inch Hale indicators; (2) an investigation by San- 
telescope were completed late in 1949, and dage of the absolute magnitudes of the 
most of the auxiliary equipment such as distance indicators by means of color-mag- 
spectrographs and photometers was fin- nitude studies in globular clusters; and 
ished in the succeeding two and a half (3) a redetermination by Baum of the 
years. As rapidly as equipment became stellar photometric standards used in all 
available, the various phases of the obser- magnitude measurements. Though the 
vational program were started, and most exact final results of all these steps are 
of these programs have therefore been in still not available, the preliminary results 
progress for from 12 to 42 months. Be- detailed later in this report are such as to 
cause of the time required to accumulate indicate that a drastic revision in the dis- 
the necessary groups of plates or other tance scale will be necessary; that is, that 
observations and to measure and interpret the distances of all objects outside our own 
them, however, very few final results had Milky Way system must be increased by 
been obtained prior to the current year. approximately a factor of 2. The revision 

In general these observational projects applies, however, to the "unit of distance" 
have been parts of the two broad programs only and does not affect the relative dis- 
of the Observatories as outlined on pages tances now assigned to the various nebulae. 
7 to 9 of the annual report for 1 948-1 949 This change in the distance scale is of 
(Year Book No. 48). A very substantial very fundamental importance to all cos- 
portion of the observing time of the Hale mological problems, since it not only in- 
telescope during moonless nights has been creases the distance of all extragalactic 
devoted to removing the outstanding un- objects by a factor of 2, but also increases 
certainties in the distance scale of the extra- their linear dimensions by the same factor, 
galactic nebulae. This has involved a It also doubles the mass of these nebulae 
thorough re-examination of each step of and increases their luminosity by a factor 
the process and has included: (1) the of 4. Furthermore, if we assume that the 
identification of the stellar types used as observed red shifts of the spectra of these 
distance indicators in the Andromeda neb- nebulae represent true recessional veloci- 
ula by Baade assisted by Miss Swope, and ties, and if we combine these velocities 
in a few more distant nebulae by Hubble with the new values of the distances to 
and Sandage, followed by a redetermi- determine the time that has elapsed since 
nation of the apparent magnitudes of these the objects left a common origin, we now 



CARNEGIE INSTITUTION OF WASHINGTON 



arrive at a value of 3.5 or 4 billion years. 
This is double the former value. If this 
time is interpreted as the age of the uni- 
verse, the new value removes much of the 
discrepancy that existed between the for- 
mer value and the age of the earth as 
determined by radioactive measurements. 

Though a small part of this revision in 
the distance scale was brought about by the 
increased accuracy of present photoelectric 
measurements over the older photographic 
methods, the major part of the change 
arises from the elimination of large un- 
certainties in the absolute magnitudes of 
the stellar types used as distance indicators 
in the earlier investigations. The earlier 
studies were made possible by Hubble's 
discovery, in the Andromeda and other 
nebulae, of long-period cepheids whose ab- 
solute magnitudes were known approxi- 
mately from statistical studies of the proper 
motions and radial velocities of a few such 
stars in the galactic system. Although the 
absolute magnitudes, or, more precisely, 
the zero point of the period-luminosity 
relation, of the cepheids were determined 
thirty-five years ago and have been under 
more or less constant scrutiny ever since, 
no major revisions were clearly indicated 
prior to the investigations discussed in this 
report. 

During World War II, Baade, using 
newly developed red-sensitive plates, had 
been able to resolve the nucleus of the 
Andromeda nebula into stars for the first 
time. These studies led Baade to the con- 
cept that the great spiral nebulae such as 
our own Milky Way system or the An- 
dromeda nebula are made up of two types 
or populations of stars. Population I is 
found along the spiral arms and has as its 
most conspicuous feature the blue giant 
stars. Population I is also accompanied by 
great clouds of gas and dust. The stars in 
the nucleus of the nebulae and between the 



spiral arms are of population II, which has 
as its most outstanding feature the red 
giants. 

This new understanding of stellar types, 
combined with the greater power of the 
200-inch telescope, has made it possible to 
follow a new procedure the first step of 
which was a direct comparison of the ap- 
parent magnitudes of many of the dwarf 
stars in a near-by globular cluster with 
the magnitudes of stars of the same type in 
the immediate neighborhood of the sun. 
Since the distances of these stars in our 
neighborhood are known from trigono- 
metric parallax measurements, this com- 
parison gives an accurate value for the 
distance of the globular cluster. In the 
second step a similar comparison of the 
magnitudes of the brightest stellar types in 
the globular cluster, all of which belong 
to population II, with the corresponding 
types in the population II regions of the 
Andromeda nebula yields a value for the 
distance of Andromeda which is independ- 
ent of the earlier very uncertain values of 
the absolute magnitudes of the cepheids. 

One important by-product of this study 
by Arp, Baum, and Sandage of the prop- 
erties of stars of the globular clusters has 
been a detailed determination of the color- 
magnitude relations in the stars of these 
clusters which are of population II. This 
has brought to light marked differences 
between these relations for the two popu- 
lation types. Likewise, the great light- 
gathering power of the Hale telescope 
combined with the speed of its spectro- 
graphs has made it possible to begin for 
the first time studies with moderate dis- 
persion of the spectra of population II stars 
as represented by stars of the clusters. Re- 
sults already obtained suggest substantial 
differences in the chemical composition 
and other characteristics of the two popula- 
tion types. 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



OBSERVING CONDITIONS 

The precipitation on Mount Wilson was 1953- During the same period observations 

again below normal, with a total of 21.20 were made with the 60-inch telescope on 

inches. Solar observations were made on 283 nights and with the 100-inch telescope 

336 days between July 1, 1952 and June 30, on 310 nights. 



SOLAR RESEARCH 



Solar Photography 



Solar observations were made by Cragg, 
Hickox, Nicholson, and Richardson. The 
numbers of photographs of various kinds 
taken between July 1, 1952 and June 30, 
1953 were as follows: 

Direct photographs 662 

Ha spectroheliograms of spot groups, 

60-foot focus 692 

Ha spectroheliograms, 18-foot focus. . 1,020 

K2 spectroheliograms, 7-foot focus . . . 53,000 

K2 spectroheliograms, 18-foot focus. . 1,017 

K prominences, 18-foot focus 978 

Solar Activity 

The magnetic classification and study of 
sunspots and related phenomena have been 
continued by Nicholson and Cragg. Co- 
operative programs have been carried out 
with the U. S. Naval Observatory, the Ob- 
servatory of Kodaikanal, the Meudon Ob- 
servatory, the University of Michigan, and 
the Central Radio Propagation Laboratory 
of the National Bureau of Standards. 

During the calendar year 1952, solar ob- 
servations were made at Mount Wilson on 
316 days, 17 of which were without spots. 
The total number of spot groups observed 
in 1952 was 219, which was 75 less than 
in 1951. The southern hemisphere with 115 
groups was slightly more active than the 
northern with 104. 

The sunspot curve for this cycle fits that 
of the last cycle most closely with a time 
displacement of a little less than ten and 
one-half years, the activity in mid 1952 
matching in phase that of early 1942. 



Therefore the first spots of the next cycle 
may be expected late in the summer or 
early in the fall of 1953, with the minimum 
coming in 1954. 

The monthly means of the number of 
spot groups observed daily for the past two 
and one-half years are shown in table 1. 

TABLE 1 



Daily number 



Month 



January. . 
February . 
March .... 

April 

May 

June 

July 

August. . . 
September 
October. . . 
November . 
December. 



1951 


1952 


1953 


4.0 


2.8 


2.4 


4.5 


2.0 


0.5 


4.2 


2.0 


1.2 


5.7 


2.2 


2.3 


7.0 


2.2 


1.2 


5.5 


3.8 


1.9 


5.4 


3.5 




4.9 


5.1 




6.4 


2.7 




4.3 


2.0 




5.2 


1.6 




3.4 


3.1 





Yearly average 5.0 



2.8 



Seventeen solar flares of intensity 1, five 
of intensity 2, and none of intensity 3 were 
recorded at Mount Wilson in 1337 hours of 
observing. The average number of flares 
recorded per 100 hours of observing was 
1.6 in 1952, 2.3 in 1951, and 5.5 in 1950. 



Sunspot Polarities 

Magnetic polarities in each spot group 
have, as far as possible, been observed at 
least once. The classification of groups 
observed between July 1, 1952 and June 30, 



6 



CARNEGIE INSTITUTION OF WASHINGTON 



1953 is indicated in table 2. "Regular" 
groups in the northern hemisphere are 
those in which the preceding spot has S 
(south-seeking) polarity and the following 
spot N polarity; in the southern hemi- 
sphere the polarities are reversed. 

TABLE 2 



Hemisphere 


Regular 


Irregu 


lar 


Unclassified 


North 

South 


62 
49 


1 






20 
32 


Whole sun . . 


111 


1 




52 



Solar Granules 

The direct photographs of the sun taken 
since the minimum of 1934 have been ex- 
amined by Richardson to obtain plates 
suitable for a study of the solar granula- 
tion. These plates have been marked in 
the plate catalogue so that they are avail- 
able at once to anyone desiring images of 
exceptional definition. 

Microphotometer tracings were made on 
plates taken throughout the present cycle, 
which began about 1943. The average 
width of a granule obtained by measuring 
the interval from maximum to maximum 
on 21 runs was 2V9 with a standard devia- 
tion of ±i"o. The distribution in size 
around the mean was nearly symmetrical. 
If the granules are regarded as circular 
disks, this value for their size is too small, 
since the tracing will cut across them at 
random instead of along a diameter. 

No apparent difference could be seen in 
the size or distribution of the granules in 
a preliminary study of the tracings taken 
on plates scattered through the cycle- 
Direct measures on the size of the granules 
made on a measuring machine, however, 
gave an entirely different distribution in 
size from that obtained from the tracings. 
The frequency in size rises to a maximum 



at about i'.'o and then falls abruptly. This 
is about the theoretical resolution of the 
4-inch aperture lens with which all our 
direct photographs are taken, a fact which 
indicates that smaller granules might be 
found with larger resolution. 

Solar Magnetic Fields 

Magnetic studies of the sun are of value 
not only in solar physics, but for the un- 
derstanding of other magnetic stars. Much 
attention has been given by H. W. and 
H. D. Babcock to the improvement of the 
photoelectric apparatus mentioned last year 
for the detection and measurement of weak 
magnetic fields of the sun's surface. Fields 
as low as one-half gauss can now be meas- 
ured quickly and with confidence. This 
is equivalent to the measurement of Zee- 
man displacements only 0.0004 as g reat as 
the width of the Fraunhofer line itself. A 
new self -synchronous automatic scanning 
system has been added. Solar magneto- 
grams have been made nearly every clear 
day at the Hale Solar Laboratory, and de- 
velopment testing of the magnetograph has 
been carried out. 

One specific result is the definite con- 
firmation of the existence of a general mag- 
netic field of the sun, detectable only in 
high heliographic latitudes, above about 
±65°. Persistent fields, of positive polarity 
near the north heliographic pole and of 
negative polarity near the south pole, have 
been under observation for nearly a year. 
These can be interpreted only as a prop- 
erty of the sun as a whole. The intensity 
and the extent in latitude of these polar 
fields are variable; rather frequently the 
intensity is found to be weaker near one 
pole than near the other. The mean in- 
tensity has been of the order of one gauss. 
These fields arise in those regions from 
which the coronal features known as polar 
tufts are seen during eclipses. 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



At lower heliographic latitudes little or 
no evidence of a general field is found, 
but instead more localized and variable 
multipolar magnetic activity occurs, even 
in the absence of visible surface features. 
Occasional extensive weak fields are also 
observed. A considerable body of data is 
being accumulated in these magnetograms, 
and significant correlations with solar ob- 
servations of other types are being investi- 
gated. It will evidently be of value to con- 
tinue regular observations with the mag- 
netograph throughout the solar cycle. The 
design of a second installation, with im- 
provements, is now in progress. 

The Abundance of Beryllium 

The solar abundance of beryllium has 
been determined by Greenstein, in collab- 
oration with Mr. E. Tandberg-Hanssen, a 



Fulbright scholar, on plates taken by H. D. 
Babcock at the Hale Solar Laboratory. 
The solar abundance ratio Be/Li appears 
to be about 8, whereas on the earth and 
in meteorites it is about 1/6. This sur- 
prising excess of Be cannot be easily ex- 
plained. Thermonuclear disintegration of 
Be and Li at the center of the sun is very 
rapid. Only in the outer envelope of the 
sun does the lifetime of Be exceed that of 
Li appreciably. The presence of Be indi- 
cates that the circulation between the cen- 
ter and the solar atmosphere is very slow. 
To account for the known depletion of Li 
in the sun, while Be is unaffected, we must 
assume that the circulation penetrates 
down into zones at a temperature of 
3,500,000° C, but no farther. This is a 
rather special assumption, but otherwise 
the Be abundance cannot be understood. 



PLANETS AND SATELLITES 



A fast-moving asteroid (1953EA) was 
discovered by A. G. Wilson on a plate of 
the National Geographic Society-Palomar 
Observatory Sky Survey taken with the 
48-inch schmidt camera on March 9, 1953. 
Its orbit can be well determined from 
photographs taken in March by Wilson 
and Harrington with the 48-inch, in April 
by Dr. L. E. Cunningham with the 60-inch 
telescope, in May by Cunningham with the 
100-inch, and in June by Sandage with the 
200-inch telescope. 

When discovered it was 6,000,000 miles 
from the earth, but its closest possible ap- 
proach is about 3,000,000 miles, one-fifth 
that of Eros. When closest to the earth its 
magnitude is about 13. Its period is very 
nearly 4 years, and there should be no 
difficulty in observing it again in 1957. 
Unless its albedo is much less than that 
of the moon, its diameter cannot be greater 
than one-quarter of a mile. 

Positions of Jupiter's faint satellites were 



obtained by Nicholson with the 100-inch 
telescope at the 1952 opposition of Jupiter. 

The Atmosphere of Jupiter 

On the morning of November 20, 1952, 
the occultation of o Arietis (2 b 48 111 52 s , 
+ 14 53') by Jupiter was observed by 
Baum and Dr. A. D. Code, using a photo- 
electric photometer attached to a grating 
spectrograph at the Cassegrain focus of the 
60-inch telescope. This event afforded a 
rare opportunity to determine the mean 
molecular weight of the gases composing 
the outer layers of Jupiter's atmosphere 
simply by observing the rate at which light 
from the occulted star was extinguished. 
Two optical effects are involved: (1) the 
spreading of the star's light due to differ- 
ential refraction, and (2) ordinary expo- 
nential extinction due to molecular scatter- 
ing. It was shown from theoretical con- 
siderations that differential refraction is 
the dominant effect and that the rate at 



8 



CARNEGIE INSTITUTION OF WASHINGTON 



which the star fades from view depends 
only upon the geometry of the occultation 
and upon the scale height in Jupiter's strat- 
osphere. The scale height is in turn re- 
lated to the temperature and mean molec- 
ular weight. 

Observationally, the problem was to ob- 
tain a light-curve for the fading of a Arietis 
without serious interference from the thou- 
sandfold greater luminosity of Jupiter, 
against whose limb the event occurred. 
"Seeing" precluded the use of a sufficiently 
small focal-plane diaphragm to isolate the 
star from Jupiter's disk, but the difference 
between their spectra provided the means 
of discrimination needed. Since the B5 
spectrum of o Arietis has practically no 
K line of Ca 11, whereas the reflected G2 
(solar) spectrum of Jupiter has a deep 
one, monochromatic photometry at that 
wave length strongly favored Arietis. 

The best fit of the observed light-curve 
to a family of theoretical light-curves yields 
a value of 8 kilometers for Jupiter's scale 
height, corresponding to a mean molecular 
weight of 3.3. This is the first direct obser- 
vational evidence that the atmosphere of 
Jupiter consists largely of hydrogen and 
helium. 



Motion pictures of this occultation of 
Arietis by Jupiter were taken at the same 
time by Pettit and Richardson at the 
coude focus of the 100-inch. The camera 
was started operating automatically about 
15 minutes before the predicted time of 
occultation, taking exposures every 3.5 sec- 
onds. The progress of the planet toward 
the star was also followed visually in blue 
light through the eyepiece with a power of 
1500. The time determined visually was 
io h 48 111 12 s UT, in good agreement with 
that determined independently by other 
observers. The predicted time for Mount 
Wilson was io h 52.o m . 

Some 200 images were obtained, cover- 
ing the complete event. The most interest- 
ing feature of the photographic record is 
the remarkable variations in brightness of 
the star about 50 seconds before its final 
disappearance. Since a close examination 
of the star and the planetary images indi- 
cates a reasonably steady state of seeing, 
these variations have been attributed to 
turbulence in the atmosphere of Jupiter. 
Marked fluctuations in brightness were 
also observed about the same time on the 
photoelectric light-curve made by Baum 
and Code. 



STELLAR SPECTROSCOPY 



During the report year all major tele- 
scopes except the 48-inch schmidt camera 
were engaged in spectroscopic observations 
for approximately two weeks each month 
during the period when the moon inter- 
feres with direct photography and photom- 
etry. Over 560 spectrograms were taken 
with the 60-inch telescope, 960 with the 
100-inch, and 750 with the 200-inch Hale 
telescope. These spectrograms were ob- 
tained chiefly to provide information con- 
cerning the chemical compositions, tem- 
peratures, pressures, turbulence conditions, 
magnetic fields, etc., present in the at- 



mospheres of stars and in planetary neb- 
ulae. 

The great light-gathering power of the 
Hale telescope combined with the great 
optical speed of its coude spectrograph, 
especially with the shorter-focus cameras, 
has for the first time made it possible effec- 
tively to extend these studies to certain 
major new groups of objects. These in- 
clude: stars of population II, the nearest 
definite examples of which are found in 
the globular clusters; the white dwarfs; 
and the faint blue stars near the galactic 
pole. 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



Long-Period Variable Stars 

Long-exposure spectrograms, chiefly 
with the 200-inch telescope, have been 
studied by Merrill and show many details 
of the extraordinary behavior of the rich 
bright-line spectrum of the long-period 
variable x Cygni near minimum light. Of 
60 bright lines whose intensities increase 
markedly during the two months preced- 
ing minimum, one-third are forbidden 
lines of Fe 11, and two-thirds are unidenti- 
fied. Differences in radial velocity between 
various groups of lines and between plates 
at various phases are small. 

A survey by Merrill and Miss Lowen of 
numerous high-dispersion spectrograms of 
long-period variables has shown that the 
gallium line A4172.05 is regularly present, 
and that it changes during the light-cycle 
from absorption to emission in such a way 
as to indicate that the emission comes about 
through fluorescence, the exciting line be- 
ing A4033.07 of Mn 1. 

Shell Stars 

Spectroscopic observations of two in- 
teresting shell stars, 48 Librae and HD 
33232, begun many years ago, have been 
completed by Merrill. The oscillation of 48 
Librae, HD 142983, which began about 
1934 with a remarkable outward thrust of 
the atmosphere, has been clearly observed 
from 1938 to 1952. The observed outward 
motion slowly increased until in 1937 the 
velocity was about 100 km/sec; it then de- 
creased and in 1939 changed to inward 
motion. Two cycles of about 8 years each 
have now been observed, minimum veloci- 
ties (in the algebraic sense) having oc- 
curred about 1937 and 1945, maximum 
velocities about 1941 and 1950. The ampli- 
tude has diminished as if the oscillation 
were damped. At times of minimum ve- 
locity the radial velocities derived from 
successive lines in the Balmer series of 



hydrogen have a negative progression from 
Ha to W35; at times of maximum velocity 
the progression is positive. Thus the ultra- 
violet Balmer lines toward the limit of the 
series yield a larger amplitude than do the 
lines nearest to Ha. Metallic lines, par- 
ticularly those of Fe 11, yield a velocity 
curve similar to that from H2S. The curves 
for H28 and Fe 11 precede the curve for 
H6 by variable intervals averaging per- 
haps 100 days. 

The variable velocity observed in HD 
33232 is now believed to be due to a slow 
atmospheric oscillation rather than to mo- 
tion in a binary orbit as was previously 
supposed. The cycle appears to have 
lengthened from 3710 days to more than 
4000 days, minima having been observed 
about 1924 and 1948, a maximum in 1930. 
The shape of the velocity curve also ap- 
pears to have changed. The amplitude of 
the velocity curves derived from metallic 
lines and from hydrogen lines near the 
limit of the Balmer series exceeds 100 km/ 
sec. This amplitude is greater than that 
yielded by hydrogen lines near Hy, thus 
following a pattern that is probably charac- 
teristic of oscillations in shell stars. 

Other shell stars, not so extensively ob- 
served, that probably behave somewhat like 
48 Librae and HD 33232 are (3 Monocerotis 
A, HD 44351, HD 183656, and HD 220300. 

Merrill and Miss Lowen have intercom- 
pared 21 shell stars for which spectrograms 
with dispersion 10 A/mm are available. 
Relative intensities of lines of hydrogen 
and of seven metals were estimated. Lines 
of Mg 1, Ti 11, and Cr 11 have rather strong 
direct correlations, whereas those of Sen 
and Ni 11 show an inverse correlation with 
each other, although with considerable scat- 
ter. Atomic data offer a partial explana- 
tion of these facts. In 9 stars the central 
absorption of A4026 He 1 ranges from 3 to 
12 per cent, the actual width from 5 to 
12 A. 



10 



CARNEGIE INSTITUTION OF WASHINGTON 



In most shells the velocity varies slowly 
through a large range, and the structure of 
the lines shows small changes during the 
velocity cycle, wings appearing on the side 
toward which the lines are moving. In 
stable shells the lines are symmetrical and 
sharp. Atoms that form a shell probably 
drift slowly away from the photosphere, 
but, through a slight outward acceleration 
over a long interval, may in some stars at- 
tain velocities as great as ioo km/sec. The 
possible nature of the outward force was 
briefly discussed. 

SUBDWARFS AND WHITE DWARFS 

White dwarfs have been somewhat neg- 
lected in the past because of their faint- 
ness. The coude spectrograph at Palomar 
permits observation of these interesting ob- 
jects at relatively high dispersion. Green- 
stein is measuring the line profiles of the 
hydrogen lines in the brighter white 
dwarfs at 38 A/mm. The lines have wings 
about 200 A wide; in some white dwarfs 
they are relatively deep, in others so shal- 
low that even Hy and Hh are invisible on 
the plates but can be found on tracings as 
great shallow depressions. A detailed study 
of the yellow "white dwarf" Van Maanen 
2 is being made; this has a lower tempera- 
ture and shows a few metallic lines. 

The known subdwarfs down to magni- 
tude 1 1. 5 are also being observed by Green- 
stein in the range of spectral types O to G8. 
The general features of the later sub- 
dwarfs are: weak lines of the metals, lack 
of rotation or turbulence, and relatively 
great strength of hydrogen. The frequency 
of binaries seems to be small. It seems 
probable that the subdwarfs will show a 
wide range of spectral peculiarities, par- 
ticularly in the weakness of the metallic 
lines at a given temperature. Parallaxes are 
badly needed to ascertain whether the 
spectral peculiarities are correlated with 
luminosity. 



The early-type subdwarfs are extremely 
interesting. A very great range of lumi- 
nosity and spectral peculiarities exists 
among the faint blue stars. Two new 
helium-rich faint stars have been found; 
in one, some of the He 1 lines are 9 A wide, 
owing to pressure- and Stark-effect broad- 
ening. One Bo star has no detectable hy- 
drogen lines and strong helium, nitrogen, 
and silicon. 

Blue Stars near the Galactic Pole 

A number of the brighter blue stars dis- 
covered by Humason and Zwicky near the 
galactic pole have been observed with the 
200-inch coude by Greenstein and Munch. 
The stars of spectral types B8 to Ao seem 
to be normal and presumably are proto- 
types of the blue stars on the horizontal 
branch of the globular-cluster diagrams. 
The earlier stars observed have spectra that 
are somewhat peculiar, especially in the 
absence of ionized carbon. It seems pos- 
sible that some of the effects of age in these 
stars of population type II are now being 
observed spectroscopically; that is, the nu- 
clear-energy processes have resulted in the 
exhaustion of hydrogen, with formation 
of helium and possibly of carbon. The lat- 
ter will then be converted into nitrogen in 
the envelope surrounding an exhausted 
core. The early stars of population II so 
far observed seem to have only small rota- 
tion; hot stars in our neighborhood tend to 
have large rotations. 

Stars in Globular Clusters 

In order to find out whether the blue 
objects found by Humason and Zwicky at 
the galactic pole belong to the population 
of the halo of the galactic system, some of 
the blue stars in globular clusters are being 
observed for comparison by Munch. So 
far only 5 stars in M 3 and M 13 have been 
photographed with the Newtonian spectro- 
graph of the 100-inch telescope. But it is 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



II 



planned to continue this program until a been found with only thermal motions in 

fair-sized sample of spectra is obtained. its atmosphere. With high dispersion it is 

To facilitate classification, widened coude found that as the luminosity increases in 

spectra at 38 A/mm have been obtained, the G stars, the turbulence increases, the 

by Deutsch with the Hale telescope, of a rare earths strengthen more rapidly than 

number of red giants in the globular clus- other ions, and the CN strengthens. (The 

ter M 92, and of a smaller number in M 3. latter effect is greatly reduced in stars of 

The spectra in M 92 fully confirm Baum's the high-velocity group, which mimic stars 

findings on the abnormal weakness of the one luminosity class lower.) 

metallic lines and the strength of the In collaboration with Dr. L. H. Aller, a 

Balmer lines. From estimates of a number quantitative analysis of 4 subdwarfs has 

of metallic-line ratios that are sensitive to been initiated by Greenstein. The spectra, 

temperature, however, it is found that the at 10 A/mm, are of HD 19445, 140283, 

excitation temperatures of these stars are 161817, and 219617. Three of these are the 

not greatly different from their color tern- so-called "intermediate white dwarfs" of 

peratures. To the extent that their spectral Mount Wilson Contribution No. 511; HD 

types indicate excitation temperatures, the 161 817 is a star of very high velocity, 

types of these stars may therefore be said Coude spectra of most of the metallic- 

to be in fair accord with their color classes, line stars in the Hyades and in the Coma 

The material at hand, including many Berenices cluster have been examined by 

spectrograms by O. C. Wilson and Bowen, Deutsch. The apparent abundance anom- 

tends to support the thesis of Sandage and alies found by Greenstein from an analysis 

Schwarzschild that the metals-to-hydrogen of the spectrum of t Ursae Majoris appear 

ratio is appreciably lower in M 92 than in not to be a common feature of all these 

the other globular clusters studied, and objects, and there is considerable doubt 

that this ratio varies systematically from whether elements with second ionization 

cluster to cluster in a way that is correlated potential in the neighborhood of 13.5 volts 

with the position of the red-giant branch show a common behavior, as Greenstein 

in the color-magnitude diagram. found to be the case in t Ursae Majoris. 

In the open cluster NGC 663 measures 

Chemical Abundances and Physical Con- have been made by Deutsch of the param- 

ditions in Stellar Atmospheres eters characterizing the Balmer discontinu- 

Greenstein's program for the spectropho- ity in the spectra of several of the most 

tometric measurement and first analysis of luminous early-B supergiants. Though the 

the composition of the normal G stars with measures are not precise, they suffice to 

high dispersion has been completed. Dr. confirm the prediction of W. Becker, based 

Jean Humblet, of the Institut d' Astro- on his heterochromatic photometry, that 

physique, Liege, added two peculiar stars these objects exhibit very abnormally 

to this program, 31 Aquilae (a so-called strong Balmer continua. The interpreta- 

A4150 star) and HD 18474, a carbon-poor tion is obscure. 

star. The turbulence of the G stars is All the observational material for the 

found to be directly correlated with the eclipses of £ Aurigae in 1 939-1 940 and in 

luminosity; turbulence is found also in the 1947— 1948 has been measured and analyzed 

high-velocity giants. It is interesting to by O. C. Wilson and Abt. The only model 

note that the subdwarf Groombridge 1830 which can be made to fit most of the 

has zero turbulence; no star had previously observational data is one in which the 



12 



CARNEGIE INSTITUTION OF WASHINGTON 



chromospheric matter occurs in condensa- 
tions of some kind. 

Spectrum Variables 

Corrections have been found by Deutsch 
for the previously published periods of two 
spectrum variables. For the "strontium 
star" x Serpentis the correct period is 1.60 
days; the older value was the beat period 
of this with one sidereal day. The new 
observations of this star also reveal that 
midway between the phases of Ca 11 maxi- 
mum and Sru maximum there appear a 
group of lines much sharper than all others 
in the spectrum, and possibly attributable 
to La 11. The correct period of the "silicon 
star" 56 Arietis is 0.726 day. In this star, 
while the silicon lines and the associated 
unidentified lines go through a single oscil- 
lation of intensity, the helium lines vary 
through two full cycles. 

An object that exhibits a spectrum simi- 
lar to that of 56 Arietis is HD 124224, 
which last year was found to have the 
very short period of 0.521 day. Radial- 
velocity measures made with the assistance 
of Miss Burd, over the half-cycle centered 
on silicon maximum, indicate that, whereas 
the Balmer lines and Mgn 4481 yield a 
constant velocity, Si 11, Fe 11, and the un- 
identified lines that vary with these yield 
velocities that change from —40 km/sec 
to +40 km/sec. 

The objects named above are 3 of the 9 
spectrum variables whose periods have 
been published. In most of these stars, the 
lines are so wide that the Zeeman effect has 
not been observed. In two of these, HD 
125248 and a 2 Canum Venaticorum, H. W. 
Babcock has found magnetic fields that 
vary synchronously with the line strengths. 
With Miss Gjellestad, he has also found 
periodic field variations in HD 153882; 
this object is not known to be a spectrum 
variable. Since all these stars are members 



of Morgan's sequence of peculiar A-type 
stars, Deutsch has grouped them together 
and has shown that the periods are closely 
correlated with the line widths. Over the 
whole range of periods from 0.5 to 20 days 
the line widths on coude spectra vary 
roughly in inverse proportion to the peri- 
ods. In fact, it appears that the widening 
of the relatively invariable lines in these 
spectra can be quantitatively understood 
on the assumption that each star rotates 
with the period of variation of its spectrum 
or of its magnetic field, and that we view 
the star from a point nearly in its equa- 
torial plane. 

Accordingly, Deutsch has been led to the 
hypothesis that the periodic magnetic and 
spectrum variables are stars having their 
magnetic axes highly inclined to their ro- 
tational axes, and having in their atmos- 
pheres large abundance anomalies which 
depend primarily on magnetic latitude. 
Additional evidence for this general pic- 
ture seems to be found in the radial veloc- 
ities of HD 124224 as well as those of 56 
Arietis and a 2 Canum Venaticorum. The 
observations of line doubling reported by 
W. A. Hiltner and other observers and the 
observations of the crossover effect in line 
contours appear to be consistent with this 
hypothesis. On the other hand, as is 
pointed out in the next section, this simple 
rotational hypothesis does not by itself 
appear to be capable of explaining many of 
the magnetic observations of these stars. 
Attempts are being made by Deutsch to 
give a theoretical account of such rotating 
magnetic fields, and to discover whether, 
by accretion of interstellar ions accelerated 
to cosmic-ray energies, these fields could 
produce the observed abundance anomalies. 

Stellar Magnetic Fields 

The observations of stellar magnetic 
fields made in the past seven years have 



MOUNT WILSON AND PALOMAR OBSERVATORIES jo 

been summarized by H. W. Babcock. Among magnetic stars showing irregular 

With the assistance of Miss Burd and Mrs. magnetic changes are HD 4174 and HD 

Deutsch, fields have been measured in 35 133029. In the latter the fluctuations are 

stars, of which 27 are peculiar objects of quite rapid. 

types A and F. Six are spectrum variables. Two interesting magnetic variables that 
All these stellar magnetic fields are variable may have an important bearing on the in- 
to a greater or lesser extent: 11 have al- terpretation of these objects are HD 71866 
ways shown a positive magnetic polarity, and HD 173650. The former has the most 
10 negative, and 14 reverse polarity from pronounced crossover effect yet found, and 
time to time. HD 173650 shows a very abnormal mag- 

The magnetic changes are regular in netic behavior of chromium. The star has 

some stars and irregular in others, with sharp lines, some of which develop faint 

pronounced spectrum variation appearing emission wings at certain phases. These 

in some but not all of the regular mag- stars are among those currently under ob- 

netic variables. The irregular magnetic servation for the determination of period 

changes can be interpreted only as the re- and amplitude. 

suit of intrinsic variations in the stellar The magnetic curve of a 2 Canum Vena- 
field, not of rotation of a star having a con- ticorum reported last year is difficult to 
stant field. Attempts to devise a physical interpret because of the relatively sudden 
model for the magnetic stars have not yet reversal, in about one-tenth of the period, 
led to a wholly satisfactory result. Here it Preliminary tests at the crossover phases 
is necessary to take into account not only failed to reveal plane polarization in the 
the magnetic variations in detail, but also line profiles, to be expected if the transverse 
the velocity and intensity effects shown by Zeeman effect predominates as in an ob- 
various elements, as well as the crossover lique rotator. Spectrophotometric meas- 
eflfect, line profiles, and variations in light ures of the lines of spectrum variables as 
and color. a function of phase are lacking, but partial 

For the long-period magnetic and spec- series of calibrated plates have been ob- 

trum variable HD 188041, observations tained for HD 125248 and for a 2 Canum 

have been collected for six years. Accurate Venaticorum with the aim of supplying 

measurements of the field are possible be- such data, 
cause of the number and sharpness of the 

lines. The varying magnetic field is regu- Interstellar Lines 

lar in period but irregular in amplitude; During the fall of 1952, about 50 early- 

the changes cannot, therefore, be explained type stars in the northern Milky Way 

by rotation alone. At magnetic minimum, were photographed by Munch with the 

which recurs at intervals of 226 days, the coude spectrograph of the Hale telescope, 

polar field is about + 1400 gauss. Between in the region of either the Ca 11 or the Na 1 

minima, the field fluctuates rather irregu- lines. The study of these plates has re- 

larly from cycle to cycle, ranging upward vealed that stars between galactic longi- 

sometimes to +4800 gauss. The star is a tudes 65 ° and 135 and at distances (from 

spectrum variable, in which lines of Eu 11, spectroscopic distance moduli) of the order 

iSVn, and probably some other elements of 2 kiloparsecs show two well separated 

vary with phase. The behavior of this star and about equally strong components. In 

suggests some remote relation to the mag- comparison, near-by stars (up to distances 

netic cycle of the sun. of 1 Kpc) show only a single strong com- 



14 



CARNEGIE INSTITUTION OF WASHINGTON 



ponent. The velocities of the least dis- 
placed components in distant stars, together 
with the velocities of the interstellar lines 
in the near-by ones, in the mean, define 
quite well the galactic-rotation effect on 
the radial velocity of a point at a distance 
of about 500 psc. The shift of the most 
displaced component in distant stars cor- 
responds to a galactic-rotation effect of a 
point at about 3 Kpc. 
These observations have been interpreted 



by Munch as indicating that the interstellar 
gas clouds are concentrated along the struc- 
tural features outlined by Morgan, Oster- 
brock, and Sharpless as the spiral arms of 
the galactic system. Further observations 
are being carried out in order to extend the 
range of galactic longitude where the large- 
scale arrangement of the interstellar gas 
clouds may be detected, and also to esti- 
mate the degree of concentration of the 
clouds along the spiral arms. 



NEBULAR RESEARCH 



Highlights in the year's work are repre- 
sented by: (1) a definitive value for the 
order of the unit of absolute distance in the 
scale of extragalactic distances, (2) rapid 
development of investigations of globular 
clusters, and (3) successful trials of a new 
"photon-counting" photometer which per- 
mits accurate measures of luminosities to 
the extreme limits of photography, and 
probably beyond. The first item is the re- 
sult of a sustained program of investiga- 
tions which has now furnished a funda- 
mental datum for mapping the sample of 
the universe that can be observed. The 
second item not only has established the 
unit of distance, but is rapidly building up 
our first picture of a pure type II stellar 
population, and is contributing important 
clues to stellar evolution. The third item 
opens to investigation many quite new 
fields near the threshold of photography, 
of especial interest in problems of cosmol- 
ogy and evolution. 

RADIO SOURCES 

As was mentioned in the last annual re- 
port, Baade found a remarkable nebulosity, 
apparently a chaotic mass of short fila- 
ments, in the position of the strong radio 
source Cassiopeia A. Minkowski has made 
a spectroscopic study of the nebulosity and 
finds that it represents a new type of object. 



Individual filaments show large internal 
motions; in one, about 2" wide and 20" 
long, velocities range from —1000 to at 
least +2200 km/sec. The spectrum of this 
filament is unusual, showing lines of [O 1] 
and [O in] about equally intense and at 
least five times stronger than the unob- 
served [On] lines and Ha. Other fila- 
ments show smaller internal motions and 
less anomalous spectra. The velocity differ- 
ences between filaments are so small rela- 
tively to the spread within filaments that 
no decision is permitted as to whether the 
nebulosity as a whole is expanding. If the 
object is expanding, the velocity of expan- 
sion is obviously small as compared with 
the internal random motions; this condi- 
tion is just the reverse of that found in 
shells around novae and supernovae. 
Therefore, it is not permissible to assume 
that the nebulosity is a supernova shell. 
Nor can it be such a shell decelerated by 
interaction with interstellar gas. To con- 
vert the velocity of expansion almost en- 
tirely into random motions, an interstellar 
cloud of outstanding density would be 
needed, and evidently the nebulosity is not 
inside a cloud of this type. 

The radiation emitted by Cassiopeia A 
has been studied by Dr. L. H. Aller and 
Minkowski, who report that it appears to 
be derived from the kinetic energy of free 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



15 



electrons. The spectrum may be under- 
stood if the electron density lies between 
io 3 and io 4 per cubic centimeter, and if the 
electron temperature is less than 15,000° C. 
Dissipation of mechanical energy in the 
filaments may serve to maintain this elec- 
tron temperature. 

Minkowski and Greenstein have esti- 
mated that the energy emitted per unit 
volume by some of the strongest radio 
sources is of the order of io -22 erg per 
cubic centimeter. This rate is higher by 
many orders of magnitude than that for 
the galactic system. Compared with the 
nonthermal radiation associated with sun- 
spots, the radiation per unit volume of the 
strongest sources is weaker by a factor of 
the order of io 12 , but the radiation per 
unit mass is about the same. The kinetic 
energy available in the collision of gas 
clouds at high velocities is large as com- 
pared with the maximum radio emission 
observed. Finally, the Cygnus radio source, 
identified by Baade and Minkowski as a 
pair of stellar systems in collision, emits 
more energy in the radio-frequency spec- 
trum than in the visual spectrum. Similar 
collisions could be detected by radio tech- 
niques at distances beyond the limit 
reached by photography with the 200-inch 
reflector. 

STELLAR PHOTOMETRY 
Photometric Standards in Selected Areas 

Baum reports that the photoelectric 
standardization of stars in ten Selected 
Areas is now observationally complete to 
magnitude 19. On the average there are 
4 stars per magnitude interval in each area, 
making a total list of about 400 stars. Re- 
duction of the measures to magnitudes and 
colors on the International System has been 
under way for more than a year and is 
now about three-fourths complete. These 
magnitude sequences will be used as the 



fundamental standards for Hubble's cur- 
rent photographic work on clusters of neb- 
ulae, for Baade's work on cepheids in the 
Andromeda nebula, and for a variety of 
other photographic investigations. The new 
photon-counting photometer described un- 
der "Instrumentation" will now be used 
for providing extended sequences between 
magnitude 19 and the plate limit in three 
of the ten areas. 

The Variable Stars h Ceti and UX 
Ursae Majoris 

Under the general heading of photom- 
etry may also be mentioned photolectric 
observations by Walker of two variable 
stars. One, h Ceti, was followed on two 
nights with the 20-inch reflector on Palo- 
mar and was found to vary through a 
range of about 0.025 mag. Though a 
unique period could not be determined, 
the data are consistent with the period of 
0.16122 day found by Henroteau for the 
variations in radial velocities. These facts 
make it probable that the star is a member 
of the (3 Canis Majoris class. 

The second variable, the eclipsing star 
UX Ursae Majoris, was observed in the 
yellow, blue, and ultraviolet on seven 
nights with the 60- and 100-inch reflectors. 
The data confirm several peculiar features 
of the light-curve and the short-period in- 
trinsic fluctuations in brightness discovered 
by Linnell, and contribute several new 
features, including a bright shoulder on 
the curve before the eclipse, in addition to 
the previously known shoulder following 
eclipse. The intrinsic fluctuations in bright- 
ness are irregular in length, the interval 
between successive maxima varying from 
1 to 15 minutes. Amplitudes in the ultra- 
violet (observed as large as 0.18 mag.) are 
about three times those in the yellow. 
These fluctuations together with the bright 
shoulders on the light-curve suggest that 



i6 



CARNEGIE INSTITUTION OF WASHINGTON 



the attraction of the secondary produces a 
bright, unstable spot on the surface of the 
primary star beneath. 

The depths of the minima are 1.02, 1.10, 
and 1.22 mag., in the yellow, blue, and 
ultraviolet, respectively, measured from 
constant light. Although there is no phase 
lag in the time of minimum light in the 
different colors, discrepancies between ob- 
served and predicted times of minimum as 
large as 5 minutes have been recorded. The 
nature of these shifts cannot be determined 
from the limited data now available, and 
it is hoped to continue the study during 
the next season. 

PLANETARY NEBULAE 

O. C. Wilson has assembled high-disper- 
sion spectra covering the lines Ha, Ni, and 
N2, with the 73-inch camera (4.5 A/mm) 
at the coude focus of the 100-inch, of sev- 
eral of the brighter planetaries (IC 418, 
NGC 6210, 6572, and 7009) in an attempt 
to derive an upper limit to the kinetic tem- 
peratures. He has also obtained slit spectra 
of planetaries of faint surface brightness, 
too faint to be observed on Mount Wilson, 
with the 18-inch camera (18 A/mm) at 
the coude focus of the 200-inch. This new 
material suggests that the fainter nebulae 
have larger expansion velocities than the 
brighter ones (e.g., 7 fainter nebulae aver- 
age 70.5 km/sec and 18 brighter ones aver- 
age 43.7 km/sec). These velocities refer 
chiefly to the Ni and N 2 lines. 

Following the successful trial of a multi- 
slit for the 32-inch camera at the coude 
focus of the 100-inch, a similar device is 
being constructed for the 6-foot camera 
at the coude focus of the 200-inch. It will 
be used by O. C. Wilson to photograph a 
number of the brighter planetaries, and 
this material, in conjunction with slitless 
spectra, should provide data on the spatial 
distribution of the nebular matter. Dr. 
L. H. Aller will collaborate on this work. 



EMISSION NEBULAE IN THE 
GALACTIC SYSTEM 

From an examination of 48-inch schmidt 
plates centered on the galactic plane and 
completely covering the range from longi- 
tude 315 ° to 105 °, Sharpless has catalogued 
143 galactic emission nebulae and has iden- 
tified several hundred early-type stars asso- 
ciated with them. Direct photographs of 
a number of these nebulae were made with 
the 60-inch in a search for small associated 
clusterings of early-type stars that might 
be used for estimates of spectroscopic paral- 
laxes. 

As part of an investigation of the dis- 
tribution of interstellar hydrogen in the 
neighborhood of the sun, Sharpless ob- 
tained low-dispersion spectra of a number 
of stars associated with the emission nebu- 
lae IC 410, IC 1805, IC 1848, and four 
others found on 48-inch plates. The spec- 
tra furnished apparent distance moduli, 
which, when combined with photoelectric 
magnitudes and colors, will furnish paral- 
laxes of the nebulae. 

GLOBULAR CLUSTERS 
Messier 92 

The first color-magnitude diagram for 
a globular cluster to be completed and pub- 
lished in the new program was that for 
M 92, representing a joint investigation by 
Arp, Baum, and Sandage. The data 
assembled are accurate magnitudes and 
colors derived from photographic inter- 
polations between photoelectric standards. 
They range from the top of the red-giant 
branch at M pv = — 3 down to a segment 
of the main sequence at +4, and they 
show how the subgiant branch joins the 
main sequence in a globular cluster. The 
variable-star gap in the horizontal branch 
is conspicuous, a range in color (P — V = 
+ 0.12 to +0.23) containing more than a 
dozen cluster-type variables but no non- 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



17 



variables. Of the 7 globular clusters for 
which considerable data are now available, 
M 92 is the most abnormal in the sense 
that the stars differ most markedly from 
those in the solar neighborhood. This ab- 
normality, although significant for the 
study of type II populations, makes the 
fitting of the diagram for the cluster to that 
for stars in the solar neighborhood so am- 
biguous that estimates of absolute magni- 
tudes in the cluster are subject to consider- 
able uncertainties. 

Messier 3 

In M 3, however, the stars appear to be 
more normal, and Sandage, who has com- 
pleted his study of the cluster, has derived 
a mean absolute magnitude of cluster-type 
variables, M pv = +0.1 ±0.2. This result was 
obtained by fitting the subgiant branch and 
its junction with the main sequence in the 
diagram for the cluster and for the near-by 
stars. It is considered to be reliable within 
the assigned probable error, and, of course, 
it establishes the absolute magnitude of the 
brightest stars in M 3, in other words, of a 
type II population such as that observed 
in the Andromeda nebula, and hence fur- 
nishes a new, reliable distance for the 
spiral. 

Sandage has also derived the luminosity 
function for M 3 from counts on 200-inch 
plates of stars within 8' from the center 
and brighter than m pv : =22.5 (about 44,500 
in all). He finds that 90 per cent of the 
total light comes from stars brighter than 
M P v= +3-8, or m pv =i9.4, but that, if the 
function can be extrapolated beyond the 
observable range according to van Rhijn's 
function for stars near the sun, 90 per cent 
of the mass of the cluster is contributed by 
stars fainter than M pv = +3.0, and most of 
the mass by stars too faint to be recorded. 
The total mass derived in this manner is 
1.4 X io 5 suns. 



Analysis of the luminosity function and 
the color-magnitude diagram supports the 
evolutional picture for type II populations 
formulated by Sandage and Schwarzschild 
from computations of stellar-interior mod- 
els carried out at Princeton in 1952. The 
application of the theory to M 3 leads to 
an age for the cluster (i.e., time since all 
stars were on the main sequence) of 
(5±i) Xio 9 years. 

The study of luminosity functions is be- 
ing extended to M 13 and M 92, and the 
necessary plates with the 200-inch have 
already been assembled. 

Period-Luminosity Relation for Type 
II Cepheids 

Arp has completed his redetermination 
of luminosities of type II cepheids relative 
to cluster-type variables by constructing ac- 
curate light-curves for 13 cepheids with 
periods longer than 1 day found in the 6 
globular clusters M 2, 3, 5, 10, 13, and 15. 
The luminosity measures, as usual, repre- 
sent photographic interpolations between 
photoelectric standards furnished by Baum, 
H. L. Johnson, or Whitford, some of 
which are unpublished. 

The curves for the 13 stars, together with 
those for 6 similar cepheids in gj Centauri, 
previously determined with great accuracy 
by W. Chr. Martin, furnish a period-lumi- 
nosity diagram in which the luminosities 
in the several clusters are all adjusted to 
the cluster-type variables (assumed to be 
equally luminous in all the clusters). In 
this diagram the cepheids appear to define 
three narrow lines (residuals less than 
± 0.1 mag.) separated from one another by 
a factor of 2 in the periods. The line on 
which a particular cepheid falls is deter- 
mined by the form of its light-curve. 

Interpretation of the diagram is specu- 
lative at present. The light-curve might be 
pictured as consisting of two or more 



i8 



CARNEGIE INSTITUTION OF WASHINGTON 



periods, each being one-half the next longer 
period, and each representing a permitted 
vibrational mode. The small differences 
in the light-curve which determine the 
line in the period-luminosity diagram on 
which the stars fall would then indicate 
which vibrational modes were dominant. 

Existing spectra of these variables (ob- 
tained by Joy) suggest that they correspond 
to classic cepheids of one-half, one-fourth, 
or one-eighth the period. For a given ab- 
solute magnitude, the light-curves for the 
type II cepheids which fall on the line for 
the shortest periods show the closest re- 
semblance to the light-curves of classic 
cepheids. This picture, with its obvious 
implications, may restore the continuity of 
physical parameters throughout the ceph- 
eid family which was recently disrupted by 
a revision of —1.5 mag. in the zero point 
for classic cepheids. 

Long-Period Variables 

Arp has also found in the globular clus- 
ters a group of variables with periods of 
around 100 days. They appear to be dis- 
tinct from the type II cepheids in that they 
fall in quite a different region of the color- 
magnitude diagram but are closely allied 
to Me variables in the general field. This 
tentative identification opens a new field of 
investigation which is being followed by 
regular observations both in the clusters 
studied for cepheids and in others as well. 

General Properties of the Bright 

Regions of Color-Magnitude 

Diagrams 

Color-magnitude diagrams were con- 
structed by Arp for 5 of the clusters he 
studied for cepheids, namely, M 2, 5, 10, 
13, and 15, each diagram containing about 
300 stars from the very brightest down to 
absolute magnitude about +1. These di- 
agrams, together with the corresponding 



portions of the diagrams for M 3 and 
M 92, furnish comparable data for 7 clus- 
ters. After allowance for relative distances 
and reddening (estimated from the posi- 
tions of the cluster-type variables, the gap 
in which they occur, or both), a compari- 
son of the diagrams indicates several fea- 
tures, some of which may have evolutional 
significance. M 3 and M 92 are known to 
exhibit a systematic difference in the color 
indices of their giant sequences, and, in this 
respect, the 5 new clusters all fall within 
this observed range: M 2 and M 15 fall 
near M 92; M 5 and M 13 fall near M 3; 
and M 10 is intermediate. A bifurcation in 
the giant sequence, near the horizontal 
branch, is suggested in all the diagrams; 
and in the diagram for M 13, where the 
measures are most accurate, the split can 
be traced nearly to the end of the giant 
sequences. The horizontal branches show 
great disparity in position, shape, and rela- 
tive population, but there appears to be a 
definite correlation between the number of 
cluster-type variables and the number of 
stars on the red side of the gap. A super- 
position of the seven diagrams shows only 
a few scattered stars brighter than the 
horizontal branch and bluer than the giant 
sequence, and it is in this region that the 
type II cepheids are found, occupying a 
roughly vertical strip above the cluster- 
type variables, with color indices (at mean 
light) ranging from +0.1 to +0.5 mag. 
Irregular variables (some with small ampli- 
tudes) fall in the giant sequence, and the 
100-day variables fall along a continuation 
of the bright end of the sequence. 

Search for Incipient Variability among 
Stars near the Variable-Star Gap 

The characteristics of stars at either edge 
of the variable-star gap in the color-magni- 
tude diagrams for globular clusters are be- 
ing investigated along two lines. Sandage 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



19 



has assembled a long series of blue and 
yellow plates of M 3 which are now being 
measured by Mr. Morton Roberts, of Occi- 
dental College. This material will permit 
a general study both of variable stars in the 
gap and of other stars in the neighborhood. 
Meanwhile, Walker has followed photo- 
electrically a few individual stars (10 in 
M 3 and 5 in M 5) lying at either edge of 
the gap. No variability has been definitely 
established (although changes of the order 
of 0.05 mag. were suspected in two of the 
stars in M 3), and the results suggest that 
the onset of variability is quite abrupt at 
the edges of the gap. 

Walker also followed a number of the 
brightest red giants in M 3 and M 92 but 
found no evidence of variability. Both 
these photoelectric programs will be carried 
on through another season. 

Photoelectric Measures in Messier 13 

Baum has measured photoelectrically 
about 30 stars in M 13, partly to establish 
magnitude standards for general use, and 
partly to permit a comparison, on the 
basis of very accurate data, of the sequences 
in the color-magnitude diagram with those 
in the diagrams for M 3 and M 92 (in 
which marked differences, both photoelec- 
trical and spectroscopical, were reported 
last year). 

As an extension of this program, tenta- 
tive measures of two very faint stars in 
M 13 (order of magnitude 22) were ob- 
tained with the new photon-counting pho- 
tometer. Both stars have absolute magni- 
tudes around + 7, yet their color indices 
are of the order of +0.5 mag. The stars 
are far too blue and faint for the main 
sequence, far too red for pre- and post- 
novae, and too bright for ordinary degen- 
erate white dwarfs. Moreover, if they are 
similar to the subdwarfs among the high- 
velocity stars, their absence from a region 



closer to the main sequence is puzzling. 
The data are unexpected and may have 
some bearing on the end product of evo- 
lution in type II population. 

Mass of Messier 92 

Twenty-three spectrograms of 15 red 
giants in M 92 have been assembled by 
O. C. Wilson for the purpose, among 
others, of deriving the mass of the cluster 
from the dispersion in velocities of its stars. 
He has now abandoned the program be- 
cause of uncertainties in the measurement 
and interpretation of the spectrograms aris- 
ing from the abnormal weakness of metal- 
lic lines. Another cluster may be substi- 
tuted, because sample spectrograms suggest 
that stars in M 3, M 13, and M 15 are 
more nearly normal than those in M 92. 
Meanwhile, the data for M 92, as they 
stand, with their probable errors of about 
2 km/sec for a single plate, indicate a mass 
of the order of 3.3 X 10 5 suns, and, in solar 
units, a coefficient mass/luminosity = 2. 
This value for the mass of M 92 is of the 
same order as the value, 1.4 X10 5 suns, 
which Sandage derived for M 3 from its 
luminosity function. 

Other Studies 

Among unfinished programs are two 
co-operative studies by Sandage and Dr. 
H. L. Johnson, of the Lowell Observatory. 
One of these concerns the peculiar galactic 
cluster M 67, in which Johnson has meas- 
ured photoelectrically, in three colors, 
about 100 stars. The data suggest a color- 
magnitude diagram with strong giant and 
subgiant sequence so peculiar that it may 
hold clues to stellar evolution. Sandage has 
obtained a series of blue and yellow plates 
with the 60-inch, which he is now measur- 
ing. The photographic data, calibrated by 
the photoelectric, should furnish the com- 



20 



CARNEGIE INSTITUTION OF WASHINGTON 



plete diagram down to the limit of the 
6o-inch measures. 

The second co-operative program aims 
at color-magnitude diagrams in the ultra- 
violet for M 3 and M 13. Sandage has ob- 
tained the ultraviolet plates with the 100- 
inch, using a band pass from A3300 to 
A3700, and Johnson is furnishing the neces- 
sary photoelectric standards on his ultra- 
violet photometric system. 

THEORETICAL INVESTIGATIONS 

The stochastic process defined by Am- 
bartsumian's model of the Milky Way 
has been the object of further study by 
Munch. A paper has been prepared in 
which the joint probability distribution of 
the brightness of the Milky Way, arising 
from parts of the system extending to dif- 
ferent distances from the observer, is eval- 
uated. 

EXTRAGALACTIC NEBULAE 
Distance Scale 

The unit of distance hitherto employed 
in expressing extragalactic distances has 
been found to be erroneous, and its value 
must be roughly doubled. The order of 
the revision is known to be correct, and 
only minor improvements can be expected 
in the future. The revision does not affect 
relative distances; in other words, it does 
not afreet the appearance of existing maps 
of the observable region, but only the scale 
on which they are drawn. These positive 
statements are the results of a long pro- 
gram of investigation on which progress 
reports have been made over the past 
several years; the fundamental significance 
of the revision justifies some further re- 
view of the subject. 

The old unit of extragalactic distance 
was based on the zero point of the period- 
luminosity curve for classic cepheids. This 



zero point had been derived in 191 8 (be- 
fore the extragalactic regions were opened 
to exploration) from the parallactic mo- 
tions of a few classic cepheids in our own 
stellar system. Although the value has 
been under more or less constant scrutiny, 
no significant revision has been found until 
quite recently. Nevertheless, discrepancies 
have been known for many years between 
certain extragalactic data based on the zero 
point of classic cepheids and corresponding 
data within our own galactic system based 
on another unit of distance associated with 
cluster-type variables in globular clusters. 
It has seemed probable that one or both of 
the units were in error, and the current 
programs were initiated in order to clarify 
the situation. The results now confirm the 
galactic unit (as to its order of magnitude) 
and radically revise the extragalactic unit. 
Baade, who has been largely responsible 
for the investigations, describes the back- 
ground and the nature of the revision as 
follows. 

With the recognition of the two types 
of stellar population in extragalactic nebu- 
lae, each containing cepheids, the first seri- 
ous doubts arose as to whether the cepheids 
associated with the different populations 
really obeyed the same period-luminosity 
relation. Two facts in particular strength- 
ened these doubts: the occurrence of 
cepheids with periods of less than a day 
(the cluster-type variables) in population 
II only, and the marked differences in the 
light-curves of the cepheids of the two 
populations for periods larger than 12 
days. Since cluster-type variables (of type 
II) had been widely used in measuring the 
dimensions of our galaxy, and type I 
cepheids had been used for the distances 
of the nearest extragalactic nebulae, it 
became of prime importance to check 
whether our yardsticks in the two popu- 
lations were actually the same. As a suit- 



MOUNT WILSON AND P ALOMAR OBSERVATORIES 21 

able test object the Andromeda nebula to an increase of all distances derived from 
was selected, because it contains the two type I cepheids by a factor of about 2. 
stellar populations side by side: population The inconsistency between the previous 
I in the spiral arms, population II in the zero point of the cluster-type variables and 
central lens and the inter-arm regions. If that of type I cepheids has been thoroughly 
our present yardsticks in the two popula- confirmed by Thackeray and Wesselink, 
tions were consistent, the same value for who were able to reach with the 74-inch 
the distance of the Andromeda nebula Pretoria reflector the cluster-type variables 
should result whether the distance indica- in the Magellanic Clouds. Again the same 
tors of population I or II were used; other- discrepancy showed up, the distance mod- 
wise, divergent values would be obtained. u li derived from the cluster-type variables 

Investigations carried out with the 200- being 1.4 mag. larger than those from the 

inch telescope during the past three years type I cepheids. That the discrepancy is 

have shown conclusively that the yard- almost entirely due to an error in the 

sticks with which we measured distances previous zero point of the type I cepheids 

in the two stellar populations are incon- has been confirmed by Mineur and more 

sistent. The distance modulus of the An- recently by Blaauw, who made use of new 

dromeda nebula, as previously derived and very accurate proper motions of 15 

from the cepheids of population I, is close type I cepheids provided by H. R. Morgan. 

to m — M = 22.4. On the other hand, the Blaauw's value for the correction of the 

distance modulus now derived from the zero point of the type I cepheids is AM = 

brightest stars of population II (the clus- —1.4, in close agreement with the value 

ter-type variables of the Andromeda neb- derived here and by Mineur. 

ula are beyond the reach even of the 200- The new determinations of the zero 

inch telescope) turned out to be m — M= points of the cluster-type variables and type 

23.9. The discordance amounts, therefore, I cepheids, which of course are not yet 

to 1.5 magnitudes. Either the zero point final, remove a number of disturbing in- 

of the type I cepheids or that of the clus- consistencies which had become apparent 

ter-type variables is in error, or both need in recent years. It is sufficient to mention 

correction. only two of them: the abnormally large 

In order to settle this question, Sandage size of our galaxy, which had no counter- 
checked the zero point of the cluster-type part among the extragalactic nebulae and 
variables by means of the color-magnitude which now falls into line with the An- 
diagram of Messier 3. Using subgiants of dromeda nebula and other giant stellar 
well determined trigonometric parallaxes systems, and the abnormally low age of the 
to fix the zero point of the M 3 diagram, universe as derived from the red-shift 
Sandage obtained for the absolute magni- constant. 

tude of the cluster-type variables M pg = In addition to Baum's work on photo- 
+ 0.1 ± 0.2, in close agreement with the metric standards in Selected Areas and the 
previously accepted value M pg = o.o. The studies of globular clusters which estab- 
discrepancy in the distance moduli of lished the unit of distance, both of which 
the Andromeda nebula must therefore be are discussed earlier in this report, the pro- 
almost entirely ascribed to a zero-point gram of the distance scale includes the de- 
error for the type I cepheids. The indi- termination of the distance of the An- 
cated correction, AM= —1.5, corresponds dromeda nebula in terms of the new unit, 



22 



CARNEGIE INSTITUTION OF WASHINGTON 



in order to calibrate the many kinds of dis- 
tance indicator found in the great spiral, 
and the determination of distances derived 
from these indicators for a sufficient num- 
ber of nebulae to furnish a usable lumi- 
nosity function for the nebulae themselves. 
This function can then be used for sta- 
tistical distances out as far as nebulae can 
be recorded. The investigations may be 
grouped according to whether they refer 
to nebulae within the Local Group or to 
more distant objects in the general field. 

Studies within the Local Group 

Baade has continued the study of vari- 
ables in the Andromeda nebula and has 
initiated a similar study of nebulae with 
pure type II populations which are some- 
what nearer than the Andromeda nebula. 
These latter are important in their own 
right, and they also serve as intermediate 
steps between galactic globular clusters and 
the Andromeda nebula. He reports as 
follows. 

During the past year a beginning was 
made with the study of variable stars in 
the pure type II systems of the Local 
Group of nebulae. In addition to the 
Sculptor System, which is being studied at 
the Radcliflfe Observatory, the system in 
Fornax, the two systems in Leo, and the 
newly discovered system in Draco at R.A. 
17 11 19.4 111 , Dec. +57° 57-7 (1950.0) are near 
enough so that the cluster-type variables 
can be observed at the 200-inch telescope. 
All these are dwarf systems. As examples 
of type II systems of intermediate bright- 
ness, NGC 185 and NGC 205 were se- 
lected. In these systems the cluster-type 
variables are beyond the reach of the 200- 
inch telescope. They are so rich in vari- 
ables of higher luminosities, however, that 
their investigation should supplement the 
data derived from the dwarf systems in a 
most desirable manner. 



Miss Swope began the investigation of 
the variables in the bright spiral arm at the 
south-preceding end of the Andromeda 
nebula and derived during the year the 
light-curves of 176 variables, among which 
were 123 cepheids, 14 eclipsing systems, 6 
irregular variables, and 1 nova. Dr. Sergei 
Gaposchkin, who spent three months as a 
guest investigator at the Observatory, esti- 
mated the magnitudes of the variables in 
the third Andromeda field, which lies 
north of Miss Swope's field and slightly 
overlaps it. 

Because the results thus far obtained by 
Miss Swope clearly indicated that, on ac- 
count of the absorption present in the in- 
ner spiral arms of the Andromeda nebula, 
the cepheids show a considerable scattering 
with respect to the period-luminosity rela- 
tion, observations of a fourth field were 
started. This field, located in an outer 
spiral arm, at a distance of 96 minutes of 
arc south-preceding the nucleus, should be 
essentially free from obscuration, since ex- 
tragalactic nebulae appear in large num- 
bers. The cepheids of this field should lead 
to an unbiased determination of the dis- 
tance of the Andromeda nebula. 

Bright Irregular Variables in the 
Andromeda Nebula 

A study of 5 bright irregular variables in 
the Andromeda nebula and M 33 by Hub- 
ble and Sandage seems to define a new 
class not previously recognized. The char- 
acteristics include : (1) high absolute lumi- 
nosity, M pg (max) = — 8.3 ±0.2 (A.D.) on 
the new distance scale; (2) blue color, or 
at least negligible color indices; and (3) 
F-type spectra with suggestions of P Cygni 
type features. Light-curves covering the 
interval 1916 to 1953 show small ampli- 
tudes (Am ^ 2 mag.) and irregular be- 
havior. At maxima, they are among the 
very brightest stars in the two spirals, and 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



23 



this fact together with the small dispersion 
makes them useful as rough distance indi- 
cators. Similar variables are known in 
M 81, NGC 2403, and several members of 
the Ursa Major Cloud and the Virgo 
Cluster. 

Novae in the Andromeda Nebula 

The long-planned systematic search for 
novae in the Andromeda nebula and sev- 
eral other members of the Local Group 
was initiated in June 1953 by Arp. Using 
the 60-inch, he is assembling photographs 
on every night during the entire observ- 
ing season, moon and weather permitting. 
Fifty plates during June and July yielded 
three novae, all caught on the rise and, 
consequently, carefully followed through 
their maxima. Based on a preliminary 
magnitude sequence, the maxima fell be- 
tween m pg =i5.5 and 16. Two of the no- 
vae were "slow" and the other was "fast." 
Near maxima, photovisual magnitudes 
were also derived. This program, carried 
on for perhaps two seasons, is expected 
to furnish group characteristics of normal 
novae as well as to catch suitable specimens 
for spectrographic investigations. 

Studies beyond the Local Group 

Continued observations of the M 81 
group of nebulae, the Ursa Major Cloud, 
and the Virgo Cluster have produced a 
wealth of photometric material, but re- 
duction and analysis await the final deter- 
mination of standards in two of the Se- 
lected Areas. Hubble and Sandage, who 
are carrying out the investigations, found 
only one nova in M 81 during the observ- 
ing season of about five months, in con- 
trast with the six or seven found in each 
of the three preceding seasons. 

Blue Supergiants in Type I Populations 

The brightest resolved objects in two 
nebulae, NGC 2903 and 4214, were studied 



by Sharpless on plates taken in three colors 
with the 100-inch. Photographic magni- 
tudes of the bright blue stars led to a lumi- 
nosity function which agrees well with the 
van Rhijn function when the new scale of 
distance is applied. NGC 2903 is a late-type 
spiral, apparently isolated, and NGC 4214 
is an irregular nebula (resembling the 
Large Magellanic Cloud) in the Ursa Ma- 
jor Cloud. 

Total Magnitudes and Colors of 
Nebulae 

With the absolute unit of distance es- 
tablished, the problems of determining ex- 
tragalactic distances are reduced to those 
of deriving relative distances from relative 
apparent luminosities, first of the indi- 
vidual indicators found in nebulae, and 
ultimately of the nebulae themselves. The 
procedure emphasizes the importance of 
measures of total apparent magnitudes, 
and experience has shown that total mag- 
nitudes must be associated with the specific 
diameters in order to have real significance. 
Photoelectric measures through a series of 
successively larger apertures, or some 
equivalent technique, seem to offer the 
most promising approach to the problem. 

During the year Pettit has prepared for 
publication a list of total magnitudes and 
colors for about 600 nebulae, including 
most of those for which red shifts are 
known and many of the brightest nebulae 
in the nearer clusters. Many of the older 
measures have been repeated using larger 
apertures, outstanding anomalies have been 
re-examined, nuclei of 127 nebulae have 
been newly measured; and, finally, the 
color equation of the most used cell has 
been reinvestigated using 54 stars in the 
North Polar Sequence with known spectral 
types, and was found to have remained 
constant. 

The nuclear colors ranged from +0.37 
to +1.5 1, with 46 per cent redder than 1 



24 CARNEGIE INSTITUTION OF WASHINGTON 

magnitude. In general, the nuclei are red- countered in attempting to define the 

der than the nebulae (only 12 per cent are "total" magnitude of a nebula on account 

bluer). of the nature of its radial spread. Recent 

For 150 elliptical nebulae, there appears photoelectric measures by Baum using 

to be a definite correlation between color graduated concentric apertures indicate 

and total magnitude, C.I. = 0.04 (m p <r — 9) without any doubt that typical nebulae 

+ 0.84; the deviations may reach +0.2 extend far beyond the diameters within 

mag., and four are unaccountably large, which previous magnitudes have been 

Spirals are systematically bluer than ellip- measured, and that the observed magni- 

tical nebulae. Subject to a very large scat- tudes are very materially dependent on the 

ter, the data for spirals might be repre- degree to which outer regions are included, 

sented by C.I. = 0.08 (m pg — 9) + 0.50. Any systematic dependence of inclusive- 

The 19 irregular nebulae in the list are ness on distance would result in non- 

not restricted to two color levels, as has linearity in the distance scale; it could 

sometimes been suggested, but suggest a easily nullify the nonlinear term in the 

tendency to get bluer with faintness. present red-shift relation. 

Because red magnitudes in very faint No clear-cut criterion for the "total" mag- 
clusters are desirable for formulating the nitude of a nebula seems to be available, 
law of red shifts, and photocells do not yet As a function of angular-diaphragm diam- 
reach the required limit, a jiggle camera eter d, the integrated luminosities L of 
was constructed for use at the prime focus typical Eo nebulae have been found photo- 
of the 200-inch. This device builds up electrically to follow the form L — Lq-\-\ 
smooth square images of stars and nebulae, log (d + d ), which diverges instead of 
J/2, 1, 2, or 4 mm on a side, as desired. The converging to an asymptotic total. In a 
plan was to derive blue, yellow, and red typical cluster it was found that the only 
magnitudes, using two different sizes of limit to this relation is the blending of the 
image, of the twenty or so brightest nebu- outskirts of a nebula into the outskirts of 
lae in distant clusters with measured red its neighbors, and that faint nebulae are 
shifts, and to calibrate the blue or yellow as extensive as brighter ones. Estimates of 
magnitudes or both with photoelectric "total" magnitude in accord with this effect 
measures in the hope that the calibrations of mutual limitation would depend on 
could safely be extended to the red. Three- local compactness in the cluster, 
color magnitudes have been measured by When integrated magnitudes are plotted 
Hubble and Sandage with the jiggle cam- against log d for each of two similar nebu- 
era in two of the clusters, and two-color lae, the relative displacement of the two 
magnitudes in several others, but the prob- curves yields the ratio of their distances, 
lems of calibration are not yet solved, without any assumptions regarding "total" 
Baum, who has been investigating the diffi- magnitudes or any preselection of aper- 
culties, presents a special report. tures to be used for comparative measures. 

The relation between red shift and dis- The same corrections for spectral-energy 

tance has thus far been investigated using shift, recession factor, and so on, must, of 

"total" apparent magnitudes of comparable course, be utilized as before. Not only is 

nebulae to determine their relative dis- the ratio of distances obtained, but the in- 

tances. The magnitude scale itself is now trinsic similarity of the nebulae is checked 

on a firm basis by virtue of photoelectric simply by noting whether the two curves 

calibration, but serious difficulties are en- are alike. Intergalactic absorption and evo- 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



25 



lutionary fading would show up as a dis- 
agreement between Am and A log d. On 
the basis of present results, it is now clear 
that a photoelectric procedure of this sort 
will be essential to a definitive study of 
the relation between red shift and distance. 

Law of Red Shifts 

In view of the difficulties described by 
Baum, it is clear that current formulations 
of the law of red shifts must be regarded 
as approximations only. If, however, mag- 
nitudes are derived from large diameters 
or apertures, which vary more or less in- 
versely with the red shifts, they should be 
on a fairly uniform system, independent 
of distance, and the approximation in the 
law of red shifts should be correspondingly 
close. Approaching the problem in this 
manner, and using red shifts measured 
by Humason together with the most re- 
liable photometric data from all sources, in- 
cluding the jiggle-camera measures, Hub- 
ble finds the correlation log (c • dX/X) = 
o.2mio + i.i6, where mio is the photovisual 
magnitude of the tenth nebula in a cluster, 
corrected for the observed red shift only 
and not for recession, and dX/X is the 
measured shift corrected for galactic ro- 
tation only. Deviations from this relation 
are very small (order of 0.1 mag.) except 
in the case of the very sparse Pegasus Clus- 
ter, in which the residual may be accounted 
for by a size-of-sample effect. Use of the 
first or third nebulae in the clusters pro- 
duces a larger random scatter but no size- 
of-sample effect. From the displacement 
between the magnitude-red shift relations 
using brightest stars in type I nebulae (us- 
ing m Pg ) and the tenth nebulae in clusters 
(using m P v), the difference in the absolute 
magnitudes of these distance indicators is 
about 11 mag. Assuming the brightest 
stars to average about M pg = — 8 (new 
scale), the tenth nebulae should average 
about M P v= —19. 



Observations of Red Shifts 

Spectrograms of 78 extragalactic nebulae 
were obtained by Humason at the prime 
focus of the 200-inch. Many of the nebulae 
are members of distant clusters and show 
large red shifts. Additional members were 
observed in the Ursa Major No. 1 Cluster 
(R.A. n b 45 m , Dec. +55 59/) and in the 
Hercules Cluster (R.A. i6 h 3™ Dec. +17° 
56'), so that four red shifts are now as- 
sembled in the former, and seven in the 
latter. Observations of NGC 2403 were 
continued, so that velocities of six emis- 
sion patches as well as the nucleus are now 
available for determination of the mass 
from spectrographic rotation. Most of the 
remaining nebulae were observed for the 
purpose of improving results derived from 
poor-quality spectra obtained during the 
pioneer stage on Mount Wilson. 

The number of nebulae observed at 
Mount Wilson and Palomar is now 575. 
Red shifts have already been published for 
146, but many of these have since been 
revised, because of improvements in the 
methods of reducing the measures or be- 
cause of new data. All objects for which 
only one poor spectrogram was previously 
available have now been reobserved. 

Nomenclature of Red Shifts 

In the forthcoming publication of the 
data, the red shifts will be listed in the 
form c • dX/X, the shifts actually measured 
multiplied by the velocity of light. For 
small shifts, say dX/X less than 5 per cent, 
c • dX/X expresses accurately enough the 
velocity of the nebulae if the shifts are 
simple Doppler shifts. As dX/X increases, 
however, corrections (the so-called "special- 
relativity corrections") must be applied if 
c • dX/X is still regarded as a simple "veloc- 
ity of recession." These corrections grow 
rapidly, so that, for dA/A = 2o per cent (al- 
ready observed), the velocity corrected for 



26 



CARNEGIE INSTITUTION OF WASHINGTON 



special relativity is only 18 per cent that 
of light, and for cU/A = 30 per cent the 
corresponding corrected velocity would be 
only 25 per cent the velocity of light. 

The use of c • dX/X in the published lists 
will represent a compromise. All the meas- 
ures will be corrected for galactic rotation, 
which, of course, is a velocity, and the data 
will be used for many problems involving 
simple velocities (e.g., motions of near-by 
nebulae, dispersions of velocities in groups 
and clusters, etc.). On the other hand, 
cosmologists are interested primarily in 
dX/X, and will employ it differently ac- 
cording to the particular theory they are 
discussing. They are most interested in 
large values of dX/X for which secondary 
effects may be observed, whereas students 
concerned with velocities are most inter- 
ested in small values where the relativistic 
corrections are unimportant. Since it is 
inconvenient to list both red shifts and 
corrected velocities, the form c • dX/X has 
been adopted as a compromise. 

Faint Envelopes and Extensions 
around Nebulae 

Zwicky has continued his study of 
faintly luminous envelopes around nebulae, 
and of extensions including bands connect- 
ing widely separated nebulae. A number 
of long connecting bands, between nebulae 
separated by more than 4 "classic diam- 
eters," have been examined, and in no 
case has emission been detected. Conse- 
quently, the bands are composed of stars. 
Nevertheless, some of them are red and 
some are blue. This same range in color 
is found in the faint extensions around 
M 51, where, even in so near a system, the 
extensions are almost completely unre- 
solved on blue and yellow plates with the 
200-inch. These results suggest the ex- 
istence of a third type of stellar population 



whose over-all color is blue, although there 
are no blue supergiants. 

In one case of connecting bands between 
nebulae, spectrograms have furnished sur- 
prising results. This case is the triple sys- 
tem IC 3481 (Sop), Anon (Sop), and IC 
3483 (Sp). On direct photographs the 
three nebulae are clearly connected by 
long-drawn-out luminous bands. Never- 
theless, spectrograms obtained by Huma- 
son showed apparent velocities of the order 
of +7000 km/sec for both IC 3481 and 
the Anon, whereas IC 3483, fainter than 
IC 3481 and with about the same diameter, 
showed a velocity of only +134 km/sec. 
Unless IC 3483 is a small near-by dwarf 
unresolved with the 200-inch and acci- 
dentally superposed on the end of a long 
spur projecting out from the Anon, the 
spectrographic data indicate the existence 
of a very high peculiar velocity of a nebula 
(by far the highest hitherto assigned, with 
confidence, to any nebula) or some pecul- 
iar characteristic of the law of red shifts. 

INVESTIGATIONS WITH SCHMIDT 
REFLECTORS 

Internebular Matter 

Large faintly luminous clouds have been 
reported by Zwicky, spread throughout the 
central regions of several rich clusters of 
nebulae. One example is an elongated 
asymmetrical cloud, several hundred light- 
years long, within the cluster R.A. = i h o6 m , 
Dec. = —15° 40' (sometimes called the 
A-Haufen). This cloud, like the exten- 
sions from nebulae previously mentioned, 
is red in some regions and blue in others. 

A survey for variables and faint blue 
stars over a field of about 40 square degrees 
near the north galactic pole is being carried 
out by Zwicky in an attempt to identify 
stars which are clearly outside the galactic 
system, in internebular space. Incomplete 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



27 



returns suggest that variables will average 
about two per square degree between 
mpg—15 and 19.5, and results of the search 
for blue stars are regarded as satisfactory. 

Counts of Stars and Nebulae 

Zwicky has continued his counts of stars, 
nebulae, and clusters of nebulae on 18-inch 
and 48-inch film and plates, in the region 
of the north galactic pole. On i03a-O 
plates covering large areas he finds that 
stars are distributed almost at random, but 
that among nebulae brighter than m pg = 17, 
clustering is pronounced. On both blue 
and red film, average counts over large 
areas in the richest fields are of the order 
of 100 to 200 per square degree. The 48- 
inch counts of all nebulae to the limits of 
blue (i03a-O) and red (i03a-E + red fil- 
ter) plates range up to 1000 and 2000 per 
square degree over large areas (100 square 
degrees) in the richest regions. Even in 
these regions, the 48-inch counts run less 
than 30 times the 18-inch counts, and 
Zwicky adopts this as the expected ratio on 
the assumption of uniform distribution 
with no obscuration. At the galactic pole 
itself, and in some regions of the Virgo 
Cluster, the 48-inch counts drop to 500 
nebulae per square degree, which Zwicky 
considers as indicating the presence, within 
the Virgo Cluster and the Coma Cluster, of 
dark clouds of absorbing material. On this 
interpretation, the absorption within large 
clusters of nebulae such as those in Virgo, 
Coma, and Corona Borealis would be of 
the order of 0.5 mag. 

Counts of Clusters of Nebulae 

Counts of clusters of nebulae in regions 
least affected by obscuration do give a 
thirty-to-one ratio between the 48-inch and 
the 18-inch, as theoretically expected for a 
uniformly populated flat and nonexpand- 



ing universe. The additional increase in 
numbers of clusters as a function of de- 
creasing angular size, which one should ex- 
pect in the case of a real expansion of the 
universe, does not seem to be present. The 
fact that surprisingly few clusters have 
been discovered with the 200-inch telescope 
which are beyond the reach of the 48-inch 
schmidt again indicates the presence of 
intergalactic absorption, which beyond dis- 
tances of 3 X io 8 light-years (old scale) 
makes itself felt severely. Finally, Zwicky 
reports that he has determined the struc- 
tural indices of some very distant spherical 
clusters of nebulae and finds them to be 
of the same order as those for near-by 
clusters. 

Luminosity Function for Nebulae 

A luminosity function for extragalactic 
nebulae has been derived by Zwicky from 
an analysis of 156 large clusters. It was 
found to be exponentially declining for 
nebulae fainter than M pg = — 11 (old 
scale). He considers that with the dwarf 
members of the Local Group, recently 
found with the 48-inch, the luminosity 
function for near-by nebulae is very simi- 
lar to that derived from the clusters. 

Progress Report of the National Geo- 
graphic Society-Palomar Observa- 
tory Sky Survey 

During the year, 230 fields were photo- 
graphed in both red and blue with the 48- 
inch schmidt on the National Geographic 
Society-Palomar Observatory Sky Survey. 
The sky north of declination — 27 ° is now 
80 per cent covered, although the coverage 
is only 50 per cent with plates which meet 
the very high standards set for the atlas. 

Among the multitude of new objects 
found on the survey plates this year are 
three new members of the Local Group. 



28 



CARNEGIE INSTITUTION OF WASHINGTON 



They are all dwarf stellar systems resem- now known in the Local Group. Positions 

bling the Sculptor System. Their surface of the three new systems (for 1950) are : 
brightnesses are very faint, but they are all R A D 

well resolved on the 48-inch plates. Ap- I= -h 8m I( -s +67 18' 

parent diameters range up to about i°. 151327 +0 5 

Seven of these Sculptor-type systems are 17 19 24 +57 58 

INSTRUMENTATION 



During 1951 and 1952 photoelectric pho- 
tometry at the 200-inch prime focus was 
conducted by Baum using an end-on pho- 
tomultiplier tube whose output current 
was amplified by a sensitive DC feed-back 
amplifier and recorded on a strip-chart pen 
recorder. Refrigeration of the photomul- 
tiplier with dry ice greatly reduced instru- 
ment "noise" so that very small photo- 
currents could be measured. If a star image 
was bright enough to be seen distinctly in 
an eyepiece, it was centered in a focal-plane 
diaphragm (sometimes as small as 0.4 mm 
when good seeing permitted), a color fil- 
ter was interposed, and the photometer 
head was swung into place behind the 
diaphragm to obtain a deflection; a similar 
deflection for the neighboring sky was then 
obtained to determine how much back- 
ground light to subtract. If a star was too 
faint to be seen in the eyepiece, the pho- 
tometer was placed in position by measur- 
ing off its distance from a near-by brighter 
star; using this procedure, stars as faint 
as magnitude 21.8 were successfully pho- 
tometered. 

Since relatively few photons per second 
are received from faint stars and since their 
rate of arrival fluctuates randomly, the ac- 
curacy of the DC method just described 
drops off rapidly beyond magnitude 19 or 
20. This situation can be materially im- 
proved only by replacing the DC system 
with one which integrates the total light 
received (very much as a photographic 
plate does) over an observation interval of 
appreciable duration. For example, if one 



wished to measure a 22d-magnitude star 
with high precision, it would be necessary 
to count the photons received from it for 
an hour or more, to accumulate enough of 
them for statistical accuracy. 

With this end in view, the development 
of a new photometer literally to count in- 
dividual photons was carried out by Baum 
during the past year, and the new instru- 
ment was recently put into operation at 
Palomar. Like its DC predecessor, the 
photon-counting photometer employs a 
refrigerated end-on photomultiplier tube, 
focal-plane diaphragms, color filters, and 
offset motions. It is also equipped with a 
guide-scope so that a faint object can be 
kept accurately centered in a small dia- 
phragm throughout the duration of the 
count. It differs from the DC system 
mainly in the complexity of the electronic 
equipment needed to amplify the photon 
pulses, transmit them from the prime-focus 
cage to the control desk, shape them, dis- 
criminate them to remove "grass," and 
count them. The maximum registry rate 
of the system is 6000 counts per second, 
corresponding approximately to a 14th- 
magnitude object measured through a 
typical color filter. The resolution of pulse 
pairs is 5 microseconds. There is also a DC 
channel which can be used for photometer- 
ing stars brighter than magnitude 14 as 
well as for general stand-by operation. 

On June 10, sufficiently good seeing oc- 
curred to attempt reaching objects at the 
plate limit for the first time. An object 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



2 9 



(probably a nebula) whose presence was 
indicated by the barest trace o£ an image 
on a fully exposed 200-inch plate was se- 
lected for test. It was photometered with- 
out difficulty and found to be blue magni- 
tude 23; this constitutes the first direct 
measure of the photographic limit of the 
200-inch telescope. The corresponding 
limit for yellow plates would be about 
magnitude 22.5. 
Two other photoelectric photometers 



were also designed and constructed during 
the past year by Baum with the assistance 
of Walker. Both instruments employ unre- 
frigerated photomultipliers and DC ampli- 
fiers. Their use will be shared by various 
staff members interested in photoelectric 
problems. The limit for precise work with 
this equipment at the 100-inch telescope 
will be about magnitude 17, beyond which 
the new 200-inch photometer will gener- 
ally be called upon. 



GUEST INVESTIGATORS 



Following the policy of previous years, 
the Observatories have invited a substantial 
number of guest investigators from other 
institutions to make use of such telescope 
time as was not required by the Observa- 
tories' own staff. The following programs 
have been carried out by these guest in- 
vestigators. 

During the fall of 1952 Dr. Lawrence 
H. Aller, of the University of Michigan, 
made observations for his studies of plane- 
tary nebulae. In collaboration with O. C. 
Wilson he obtained a number of slitless 
spectrograms of these objects for the de- 
termination of the isophotic contours of 
the monochromatic images. The spatial 
distribution of the radiating gases in IC 418 
and IC 3568 was also estimated with the 
aid of direct photographs taken with the 
Hale telescope and loaned by Minkowski. 
Studies of the spectra of the planetary 
nuclei were made in collaboration with 
O. C. Wilson. 

Dr. Aller obtained well calibrated high- 
dispersion spectra with the 100-inch coude 
spectrograph of a number of B-type stars: 
114 Tauri, Orionis, 22 and 42 Ononis, 15 
and £ Canis Majoris, HD 36959 and HD 
36960, y Pegasi, and the O-type star 10 
Lacertae. These plates were taken for the 
purpose of obtaining improved abun- 
dances, utilizing the method of model at- 



mospheres. Additional investigations were 
made of the chemical abundances in the 
hydrogen-poor star HD 1 60041, using 
coude plates loaned by Munch. 

With Minkowski, Dr. Aller discussed 
the excitation of the optical emission spec- 
tra of the Cassiopeia A nebulosity, which 
is one of the best-known radio-frequency 



sources. 



The globular clusters Messier 53 and 
NGC 5466 were observed with the 100-inch 
reflector by Dr. James CufTey, of Indiana 
University. Photometric exposures in yel- 
low and blue light were obtained in order 
to study as accurately as possible the rela- 
tions between color index and apparent 
magnitude. The material will be supple- 
mented by further photoelectric and pho- 
tographic observations with the 36-inch re- 
flector at the Goethe Link Observatory of 
Indiana University. The faint limiting 
magnitude and the high resolving power 
of the 100-inch were essential, however, for 
a complete study of these faint, distant 
objects. 

Messier 53 is a typical globular cluster, 
rich in stars, with a concentrated, unre- 
solved nucleus; NGC 5466 is a loose clus- 
ter with an easily resolved nucleus. For an 
understanding of cluster phenomena, a 
study of objects showing extremes in physi- 
cal structure is essential, in order that the 



30 CARNEGIE INSTITUTION OF WASHINGTON 

features which depend on structure may observed with the 6o4nch reflector at 

be distinguished from the features inde- Mount Wilson in Cio, Cu, and SA 89. 

pendent of structure. Dr. T. S. Jacobsen, of the University of 

Dr. Leland E. Cunningham, of the Uni- Washington, has obtained a series of spec- 

versity of California, continued his series trograms of the cepheid variables v\ Aqui- 

of observations on comets, satellites, and lae and h Cephei. These have been taken 

unusual asteroids in September, October, with heavy exposures to bring out the de- 

and November 1952, and in January, April, tails of emission features and of the sharp 

and May 1953. The program of observa- interstellar cores associated with the H and 

tions included the following objects dis- K lines. 

covered at these Observatories : 1952c Har- Dr. Philip C. Keenan, of the Perkins 

rington, 1951k P/Wolf-Harrington, 19511 Observatory, returned to the Observatories 

Wilson-Harrington, 1950b Minkowksi, to continue his observations of S-type stars 

1953EA Wilson, two Wilson objects found begun during the preceding year. R Gemi- 

in 1951, and Jupiter X, XI, and XII. At- norum was observed during its rise to max- 

tempts were made to observe during each imum in March 1953 in order to extend 

month all current comets within reach, the measurements of wave lengths in both 

for appearance, magnitude, and position, directions from the limits of the plates ob- 

There were fewer comets than in previous tained during the preceding year. With 

years, and only 7 were definitely observed, the 100-inch coude spectrograph it proved 

Various other objects, including 5 unusual possible to obtain spectrograms of R Gemi- 

minor planets discovered elsewhere, were norum down to M v = 9.o, with a scale of 

also successfully followed. 20 A/mm, by using the spectrographic 

Dr. Sergei Gaposchkin, of Harvard Col- emulsions with maximum speed in each 

lege Observatory, made a detailed study region. Exposures were made on i03a-G, 

of the variables in one area of the An- i03a-D, io3a-F(3), and 103-U emulsions, 

dromeda nebula. For this purpose he made covering the region from 5000 to 7400 A. 

estimates of the magnitudes of a substan- A preliminary inspection of the plates 

tial number of variables on each of a long shows that there is relatively little change 

series of plates of the area taken by Baade in the lines and bands as R Geminorum 

with the Hale telescope. brightens from 8.9 m to 7.4™. 

Dr. John B. Irwin and Mr. R. R. Brown- Two additional S-type stars, HD 35155 

lee, of Goethe Link Observatory, made and HD 62164 (SU Monocerotis) , were 

2880 two-color photoelectric observations, photographed in the green region with the 

mostly with the 20-inch reflector at Palo- same dispersion in order that their radial 

mar, in a program of photometric stand- velocities might be measured for the first 

ards at +15°. The 8 brightest stars in the time. 

Harvard C-regions C7, 8, 9, 10, 11, 12, 1, With the 18-inch camera of the Casse- 

2, and 3 were observed. Numerous com- grain spectrograph of the 60-inch, the star 

parisons were made with the brighter stars HD 44544 (FU Monocerotis) was photo- 

of the North Polar Sequence, with the graphed in the green region, because previ- 

Yerkes-McDonald photoelectric standards, ous small-scale plates had suggested that 

and with the brighter stars in Selected the A5551 band of ZrO was present. The 

Areas 57, 61, 68, 71, 89, 94, and 107. In new spectrogram showed, however, that 

addition, sequences to 13.5 mag. were the features in this region are strong lines 



MOUNT WILSON AND PALOMAR OBSERVATORIES o X 

and not ZrO bands. This observation casts The program sponsored by the McMath- 
further doubt on the membership o£ this Hulbert Observatory for the study of the 
peculiar star in type S. infrared solar spectrum, using light col- 
Additional motion pictures in color of lected by the Snow telescope on Mount 
the planets Venus, Jupiter, and Saturn Wilson, continued for its fourth year. Mr. 
were obtained by Dr. R. B. Leighton, of William Livingston under the direct su- 
the Physics Department of the California pervision of Dr. O. Mohler made observa- 
Institute of Technology. Because of poor tions on 160 days between July i, 1952 and 
seeing on the nights when exposures were June 30, 1953. The limb-darkening and 
made this year, results do not represent an energy-distribution measures of Dr. A. K. 
appreciable advance over the photographs Pierce were continued through July 1952. 
obtained in previous years. An automatic In August 1952 Mr. Livingston made 
timing device has been used successfully numerous observations of the change of 
to provide equally spaced exposures of the solar molecular CO lines with distance 
equal exposure time. An automatic guid- from the sun's center. Investigation of 
ing device is under construction, the use spot spectra in the infrared also was started 
of which, it is hoped, will greatly improve at this time. 

the steadiness of the image during each Dr. Mohler installed a lead-telluride cell 
exposure. at the end of August. The infrared spec- 
Photographs were made with the 18- trum was extended to 4.8 microns with the 
inch schmidt camera by Dr. S. W. McCus- new equipment, and observations for 
key, of the Case Institute of Technology, wave-length measurement and identifica- 
to provide infrared magnitudes and colors tion of possible solar lines were begun. In 
for late M-type stars in the area near the December 1952 a new grating was installed 
galactic center. Photographs in the infra-' and applied to problems demanding high 
red with Eastman Kodak iN emulsion resolution and low intensity of scattered 
and a number 88a filter were taken for five light. A complete new set of east, center, 
adjoining areas in longitude 320° to 340 ° and west limb tracings for improvement of 
at latitude —7°. Exposures on i03a-O solar-line identification was finished. In 
film were made on the same centers to May 1953, Dr. Pierce resumed his work 
obtain blue magnitudes. The late M-type on limb darkening and intensity distribu- 
stars were identified with objective-prism tion, using improved equipment, 
spectrum plates on iN emulsion taken by At Lake Angelus Dr. Mohler continued 
Nassau in Mexico. his measurement and identification of the 
Infrared sequences have been established more than 6000 lines found in the Photo- 
by intercomparison with Selected Area 61. metric Atlas of the Near Infra-red Solar 
Measurement of the infrared magnitudes Spectrum published in 1950. All observa- 
for the late M-type stars is now under way. tions for this atlas were made by means of 
Preliminary results would indicate a very the Snow telescope, and it is expected that 
high population, from 300 to 400 per square the companion volume will be published 
degree. The limiting magnitude of the late in 1953. In June Mr. Livingston termi- 
survey is about 12.5 or 13.0 in the infra- nated his residence on Mount Wilson. He 
red. Measurements of the blue magnitudes was replaced by Mr. Dale Vrabec on June 
are also under way, and it is hoped to have 15, 1953. 

some knowledge of the colors in a few Spectrograms of a number of brighter 

sample areas within a short time. red and blue stars in the cluster M 67 have 



3 2 



CARNEGIE INSTITUTION OF WASHINGTON 



been classified by Dr. Daniel M. Popper, 
of the University of California at Los 
Angeles, and Dr. E. C. Yowell, of the Na- 
tional Bureau of Standards at Los Angeles. 
No population II characteristics are pres- 
ent. Hence this cluster is not a loose 
globular cluster as had been suggested, but 
rather a galactic cluster with a rich giant 
branch. Other observations have yielded 
a preliminary value of 1.3 solar masses 
for the mass of a normal Ko giant in the 
eclipsing system TW Cancri. This result 
tends to confirm the growing suspicion 
that the "mass-luminosity" relation is valid 
only for main-sequence stars. 

Thirty-four spectrograms have been ob- 
tained of the white dwarf 40 Eridani B, 
along with sufficient plates of standard 
stars so that the relativity displacement of 
spectrum lines may be determined on a 
sounder observational basis than hereto- 
fore. The programs on H and K emission 
lines in dwarf stars and on selected eclips- 
ing binaries are continuing. The emphasis 
in the latter program is on systems with 
components above the main sequence. 

High-dispersion spectra of several early- 
type stars were obtained by Dr. Lyman 
Spitzer, Jr., of Princeton University Ob- 
servatory, in an effort either to detect the 
interstellar Be 11 lines at A3100 or to show 
that the amount of beryllium in the inter- 
stellar gas, relative to other elements, is 
less than on the earth. Analysis of the 
material is not yet complete. In addition, 
some 40 plates of early O and Of stars 
were taken with a dispersion of 10 A/mm. 
Since these stars show normal absorption 
lines of measurable equivalent width, their 
atmospheres can be analyzed by conven- 
tional techniques; the information thus ob- 
tained should reveal the structure of these 
very hot atmospheres, and cast some light 
on the physical conditions under which 



emission lines occur in hot main-sequence 
stars. 

Dr. John Strong and Mr. William M. 
Sinton, of Johns Hopkins University, made 
preliminary measurements of planetary 
and lunar temperatures using the 100-inch 
telescope and a far-infrared spectrometer 
developed for the purpose. Observations 
were also made on the C0 2 bands at iou 
in the atmosphere of Venus. 

Dr. Otto Struve, of the University of 
California at Berkeley, has taken an exten- 
sive series of high-dispersion spectrograms 
with the 100-inch coude for a study of the 
atomic abundance in the components of 
visual double stars. Visual binaries, both 
components of which are main-sequence 
stars having approximately equal lumi- 
nosities and spectral types, were investi- 
gated to determine whether there exists 
any detectable difference in the spectra that 
might give a clue to phenomena other 
than those accounted for by variations in 
ionization and excitation. In the case of 
Y Virginis small differences in the compo- 
nents were established, the most conspic- 
uous difference being that the lines of one 
component are wider than those of the 
other. This probably represents a differ- 
ence in rotation or possibly in turbulence. 
No detectable difference in the abundance 
of the elements was found. Though h 
Equulei was not resolvable on the slit, 
high-dispersion plates taken in the summer 
of 1952 close to the passage through the 
nodes showed resolution of the lines of 
the two components in the integrated spec- 
tra. The ionization and excitation condi- 
tions are almost identical and the abun- 
dances of the elements are the same in the 
two stars. Plates have been obtained for 
about a dozen other binaries, but detailed 
studies of the spectrograms have not been 
made. 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



33 



The problem of the (3 Canis Majoris 
stars was also investigated by Dr. Struve. 
Using series of high-dispersion plates, (3 
Canis Majoris was studied to ascertain 
whether the velocity curves obtained from 
lines of different ionization potentials are 
in phase, and whether the variation in line 
width can be explained in terms of vibra- 
tion. Differences in phase of as much as 
17 minutes were found, but no conclusion 
has been reached as to the reality of pulsa- 
tions. Observations with high dispersion 
were made at Mount Wilson of the F-type 
variable h Scuti, which has a period of 4 
hours. These were supplemented by pho- 
toelectric and radial-velocity measurements 
at Lick Observatory. It seems probable 
that h Scuti represents a group of pulsating 
stars that is detached in the H-R diagram 
from the group designated as (3 Canis 
Majoris variables, which form a compact 
group between types Bi and B2, and have 
no representatives among the later B types. 
It therefore appears that there are several 
regions in the H-R diagram in which pul- 
sations occur and that there is no longer 
reason to relate these groups to the classic 
cepheids or cluster-type variables. 

Studies of line profiles in Algol, X Tauri, 
and a few other eclipsing binaries are be- 
ing carried out by Dr. Struve in an effort 
to interpret the broadening in terms of 
rotation or other causes. Other investiga- 
tions of line contours in O-type and early 
B-type stars are in progress to determine 
the relative importance of rotation and 
turbulence in producing the very wide 
lines often observed in these objects. 

Sister Mary Therese, of Mundelein Col- 
lege, has co-operated with Minkowski by 
determining precise positions of the plane- 
tary nebulae found on objective-prism 
plates with the 10-inch telescope on Mount 



Wilson and the 18-inch schmidt camera on 
Palomar Mountain. 

During the summer of 1952 Dr. A. E. 
Whitford, of Washburn Observatory, Uni- 
versity of Wisconsin, continued his study 
of the colors of distant extragalactic neb- 
ulae. Four late-type spirals with red shifts 
of 22,000 to 27,000 km/sec were found to 
be very blue in two-color photoelectric 
measurements. The color excess found by 
Stebbins and Whitford in elliptical nebulae 
is definitely absent. This is interpreted as 
the strongest support, up to now, for the 
age-effect explanation of the excess in ellip- 
ticals. The brightest elliptical system in 
the Corona Borealis cluster (V= +22,000 
km/sec) was compared photoelectrically 
with M 32 in seven filter bands whose 
centers ranged from 3400 to 8300 A. The 
resulting differential energy curve does not 
have a simple shape, but seems to indicate 
that yellow giants in the distant systems 
may be the cause of the two-color excess, 
rather than the red giants assumed in the 
first age-efTect explanation. 

Dr. A. D. Code, also of Washburn Ob- 
servatory, made three-color photoelectric 
observations of blue supergiants in M 31 in 
the fall of 1952. After elimination of in- 
ternal reddening effects, the magnitudes of 
the stars were found to be in best agree- 
ment with a modulus of 23.8 for the sys- 
tem, a value very close to that determined 
from type II cepheids. 

The redesigned photoelectric spectrum 
scanner, built around a grating spectro- 
graph, was used by Dr. Code and Dr. 
Whitford to produce intensity records of 
representative bright stars over the range 
3400 to 10,000 A, with a resolution of about 
10 A. Monochromatic magnitudes with a 
precision comparable to that in filter pho- 
tometry appear possible. 



34 



CARNEGIE INSTITUTION OF WASHINGTON 



STAFF AND ORGANIZATION 



Dr. Paul W. Merrill retired on Septem- 
ber i, 1952, after over thirty-three years on 
the stafT of the Observatory. Since 1946 he 
has been in charge of the section of stellar 
spectroscopy, and since 1950 he has been a 
member of the Observatory Committee. 

Most of Dr. Merrill's contributions have 
been in the field of the spectroscopy of 
peculiar stars with emission lines. These 
contributions have included several dozen 
articles on the spectra of long-period vari- 
ables, which have come to be accepted as 
the standard source of data on the physical 
properties of these objects. With the assist- 
ance of Miss Burwell he brought out the 
Mount Wilson Catalog and Bibliography 
of Stars of Classes B and A Whose Spectra 
Have Bright Hydrogen Lines. In addition 
to cataloguing 600 or 700 previously known 
objects, this program has found some 900 
new objects of this type through a system- 
atic survey of the sky with an objective 
prism fitted to a 10-inch red-corrected lens. 
He has also made detailed studies of the 
spectra of a substantial number of these 
early-type stars showing emission lines. 

Dr. Merrill has made significant contri- 
butions to the study of interstellar lines. 
He was among the first to investigate the 
infrared spectra of stars and nebulae and 
also was one of the first to apply inter- 
ferometer methods to the measurement of 
the separation of close double stars. 

Dr. Albert G. Wilson resigned effective 
June 30, 1953, to take a position at the 
Lowell Observatory. Since July 1, 1949, 
Dr. Wilson has been in immediate charge 
of the National Geographic Society-Palo- 
mar Observatory Sky Survey. Mr. George 
O. Abell is replacing Dr. Wilson on the 
Survey program. 

Dr. Allan R. Sandage joined the stafT 
of the Observatories on July 1, 1952. He 
has started a program of nebular research. 



Four months before his expected retire- 
ment, Mr. Albert T. Mclntire, superintend- 
ent of the instrument shop, died suddenly 
on December 21, 1952. Mr. Mclntire came 
to the Observatory in 1909 and was placed 
in charge of the instrument shop in 1937. 
Effective January 1, 1953, the instrument 
shop has been put under the supervision 
of Mr. Nichols. 

Research Division 

Solar Physics: Seth B. Nicholson, Edison 
Pettit, Robert S. Richardson, Thomas A. 
Cragg, Joseph O. Hickox. 

Stellar Spectroscopy: Paul W. Merrill, Horace 
W. Babcock, Ira S. Bowen, Armin J. 
Deutsch, Jesse L. Greenstein, Rudolph L. 
Minkowski, Guido Munch, Olin C. Wil- 
son, Sylvia Burd, Mary F. Coffeen, Dorothy 
S. Deutsch, Jean Humblet, Herbert L. Kyle, 
A. Louise Lowen, Mildred Mathews. 

Nebular Photography, Photometry, and Spec- 
troscopy: Edwin P. Hubble, Walter Baade, 
William A. Baum, Milton L. Humason, 
Rudolph L. Minkowski, Edison Pettit, 
Allan R. Sandage, Albert G. Wilson, Fritz 
Zwicky, George O. Abell, Halton C. Arp, 
Alice S. Beach, R. G. Harrington, Stew- 
art Sharpless, Henrietta H. Swope, Merle 
Walker, Paul Wild. 

Secretary of the Observatory: Milton L. 
Humason. 

Editor and Librarian: Alexander Pogo. 

Photographer: William C. Miller. 

Instrument Design and Construction 

Design: Bruce Rule, project engineer; Edgar 
C. Nichols, chief designer; Harold S. Kin- 
ney, draftsman. 

Optical Shop: Don O. Hendrix, superin- 
tendent; Floyd E. Day, Melvin W. Johnson, 
opticians. 

Instrument Shop: Albert T. Mclntire, Edgar 
C. Nichols, superintendents; Oscar Swan- 
son, instrument maker; Fred Scherff, Mur- 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



35 



doch McKenzie, machinists; Laurence E. 
Blakee, electronics technician. 

Maintenance and Operation 

Mount Wilson Observatory and Offices 
Office: Anne McConnell, administrative 
assistant; Wilma J. Berkebile, secretary; 
Leah M. Mutschler, stenographer and 
telephone operator. 
Operation: Ashel N. Beebe, superintendent 
of construction; Hugh T. Couch, carpen- 
ter; Kenneth E. DeHufT, engineer; John 
E. Shirey, janitor and relief engineer; 
Eugene L. Hancock, Alfred H. Olmstead, 
Arnold T. Ratzlaff, night assistants; 
Emerson W. Hartong, truck driver; 



Theresa Ratzlafif, Evelyn J. Blake, stew- 
ardesses; Arthur L. France, Everett W. 
McConnell, Clyde Sanger, janitors. 
Palomar Observatory and Robinson Labora- 
tory 

Office: Eleanor C. Ellison, secretary and 
librarian; Dorothea Davis, secretary. 

Operation: Byron Hill, superintendent, 
Palomar Observatory; Benjamin B. Trax- 
ler, electrician and chief night assistant; 
Charles Kearns, Robert E. Sears, night 
assistants; Harley C. Marshall, office man- 
ager; Ferd Feryan, mechanic; Gladys 
Feryan, stewardess; Ray White, power- 
house operator; George W. Pettit, jani- 
tor; Gus Weber, assistant mechanic. 



BIBLIOGRAPHY 



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Abt, Arthur. An analysis of W Virginis. Read 
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Arp, H. C. (Review) Astrophysics: The atmos- 
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William A. Baum, and Allan R. San- 

dage. The color-magnitude diagram of the 
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Babcock, Harold D. What's in the air? A. S. P. 
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See Babcock, Horace W. 

Babcock, Horace W., and Harold D. Babcock. 

Mapping the magnetic fields of the sun. 

Pubs. A. S. P., vol. 64, pp. 282-287 ( x 95 2 ); 

Mt. W. and P. Obs. Repr., No. 114. 
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See Gjellestad, Guro. 



Baum, William A. Globular clusters. I. Photo- 
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Astron. Jour., vol. 58, pp. 108-112 (1953); 
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— See Arp, Halton C. 



Beach, Alice. Planets from Palomar. Sci. 

American, vol. 188, no. 2, pp. 17-21 (1953). 
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Optical problems at the Palomar Observ- 
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Buscombe, William, and Paul W. Merrill. In- 
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Code, A. D. See Baum, William A. 

Cragg, Thomas. Convention of Western Ama- 
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36 



CARNEGIE INSTITUTION OF WASHINGTON 



Cragg, Thomas. Sunspot activity during 1952. 
Pubs. A. S. P., vol. 65, pp. 78-80 (1953). 

Deutsch, Armin J. The spectrum variable X 
Serpentis. Pubs. A. S. P., vol. 64, pp. 315-317 
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A new spectrum variable of short period, 

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The spectrum variable 56 Arietis and 

the period-line width relation. Read at 
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Cecilia Payne-Gaposchkin. Pubs. A. S. P., 

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The magnetically variable star HD 153882. 

Astrophys. Jour., vol. 117, pp. 12-20 (1953); 

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star BD +28°42ii. Pubs. A. S. P., vol. 64, 

pp. 256-259 (1952); Mt. W. and P. Obs. 

Repr., No. 87. 

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G-type stars. Read at 1952 Victoria meeting 
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(Review) Radio astronomy, by Lovell 



and Clegg. Jour. Amer. Rocket Soc, vol. 22, 

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A. S. P., vol. 64, pp. 275-281 (1952) ; Mt. W. 

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Spectroscopic observations of stars of 

class S. Astrophys. Jour., vol. 116, pp. 21-26 
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The preminimum spectrum of R Leonis. 

Astrophys. Jour., vol. 116, pp. 337-343 
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Measurements in the spectra of four 

long-period variable stars of class Me. Astro- 



phys. Jour., vol. 116, pp. 344-347 (195 2 ); 
Mt. W. and P. Obs. Repr., No. 77. 

— The low-temperature spectrum of HD 
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— Measurements in the spectra of ten shell 
stars. Astrophys. Jour., vol. 116, pp. 501- 
515 (1952); Mt. W. and P. Obs. Repr., 
No. 75. 

— Oscillations in the shell star HD 33232. 
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— Spectrograms of ten high-velocity Me 
variable stars. Astrophys. Jour., vol. 116, 
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— The spectrum of 48 Librae from 1944 
to 1952. Astrophys. Jour., vol. 117, pp. 7-1 1 
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— Research at Mount Wilson and Palomar. 
Science, vol. 116, no. 3021, prelim, p. 3 
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— Emission lines in the spectra of long- 
period variable stars. Jour. Roy. Astron. Soc. 
Canada, vol. 46, pp. 181-190 (1952); also in 
Symposium on emission-line objects, Contr. 
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344 (i953)- 

— Uber neuere Arbeiten auf dem Mt. Wil- 



son und auf dem Mt. Palomar. Phys. Blatter, 
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— Shell stars. Pubs. A. S. P., vol. 65, pp. 
113-117 (1953). 

— (Review) Sir James Jeans, by E. A. 
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— See Buscombe, William. 



Minkowski, R. The electron temperature in the 

planetary nebula IC 418. Pubs. A. S. P., vol. 

65, pp. 161-162 (1953). 
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(1952); Mt. W. and P. Obs. Repr., No. 73. 
Interstellar lines in the spectrum of the 

high-galactic-latitude star HD 93521. Pubs. 

A. S. P., vol. 64, pp. 312-315 (1952) ; Mt. W. 

and P. Obs. Repr., No. 115. 

(Review) The astronomical universe, by 



Wasley S. Krogdahl. Pubs. A. S. P., vol. 64, 

p. 327 (1952). 
Nicholson, Seth B. Daily solar observation at 

Mt. Wilson. Griffith Observer, vol. 17, pp. 

50-56 (1953). 
and Oliver R. Wulf. The role of quiet 

days in the mechanism of geomagnetic ac- 



MOUNT WILSON AND PALOMAR OBSERVATORIES 



37 



tivity. Pubs. A. S. P., vol. 64, pp. 265-270 
(1952); Mt. W. and P. Obs. Repr., No. 87. 
— and others. Summary of Mount Wilson 
magnetic observations of sunspots for March, 
1952, to February, 1953. Pubs. A. S. P., vol. 
64, pp. 205-206, 270-271, 317-319 (i95 2 ); 
vol. 65, pp. 51-53, 93-94, 162-164 (1953). 
(Review) Comets and meteor streams, 



by J. G. Porter. Jour. Amer. Rocket Soc, 
vol. 23, p. 106 (1953). 

Pettit, Edison. (Review) Across the space fron- 
tier, ed. Cornelius Ryan. Pubs. A. S. P., vol. 
64, pp. 324-327 (1952). 

(Review) Kodaikanal Observatory 190 1- 

1951, by the Director. Pubs. A. S. P., vol. 64, 
p. 328 (1952). 

and Robert S. Richardson. Motion pic- 



tures of the occultation of a Arietis by Jupi- 
ter on November 20, 1952. Pubs. A. S. P., 
vol. 65, pp. 91-92 (1953). 

Richardson, Robert S. See Pettit, Edison. 

Sandage, Allan R. The color-magnitude dia- 
gram for the globular cluster M3. Astron. 
Jour., vol. 58, pp. 61-75 (1953); Mt. W. and 
P. Obs. Repr., No. 95. 

(Review) The universe we live in, by 

John Robinson. Pubs. A. S. P., vol. 65, pp. 
55-56 (1953)- 

See Arp, Halton C. 



Sanford, Roscoe F. The spectrum and radial 
velocities of W Virginis. Astrophys. Jour., 
vol. 116, pp. 331-336 (1952); Mt. W. and 
P. Obs. Repr., No. 74. 

Richard Hawley Tucker, 1 859-1952. 

Pubs. A. S. P., vol. 65, pp. 16-18 (1953). 

Seares, Frederick H., and Mary C. Joyner. 
Photovisual magnitudes and color indices in 
42 Kapteyn selected areas. Pubs. A. S. P., 
vol. 64, pp. 202-204 (1952); Mt. W. and P. 
Obs. Repr., No. 85. 



Sharpless, Stewart. The scale of the universe. 
A. S. P. Leaflet No. 290. 7 pp. (1953). 

(Review) Statistical astronomy, by R. J. 

Trumpler and H. F. Weaver. Pubs. A. S. P., 
vol. 65, pp. 165-166 (1953). 

Swope, Henrietta H. Meeting of the Eighth 
General Assembly of the International As- 
tronomical Union. Pubs. A. S. P., vol. 65, 
pp. 11-15 (1953). 

Walker, Merle F. The light-variability of Delta 
Ceti. Pubs. A. S. P., vol. 65, pp. 49-51 

(i953). 

Wilson, Albert G. Astronomy and eschatology. 
Engng. and Sci., vol. 16, no. 9, pp. 7-10 

(i953)- 
Wilson, O. C. Some remarks on the spatial and 

kinematic structure of the planetary nebula 

IC 418. Astrophys. Jour., vol. 117, pp. 264- 

268 (1953); Mt. W. and P. Obs. Repr., 

No. 90. 
Wulf, Oliver R. See Nicholson, Seth B. 
Zwicky, F. Luminous intergalactic matter. Pubs. 

A. S. P., vol. 64, pp. 242-246 (1952) ; Mt. W. 

and P. Obs. Repr., No. 86. 

Dispersion in the large-scale distribution 

of galaxies. Pubs. A. S. P., vol. 64, pp. 247- 
255 (1952); Mt. W. and P. Obs. Repr., 
No. 86. 

Morphological features of the isothermal 

conversion of chemical energy into propul- 
sive energy. Jour. Amer. Rocket Soc, vol. 
22, pp. 339-342 (1952). 

Artificial meteors. Engng. and Sci., vol. 

16, no. 4, pp. 20-22 (1953). 

Luminous and dark formations of in- 
tergalactic matter. Phys. Today, vol. 6, no. 4, 
pp. 7-1 1 (1953). 

Neue Methoden der kosmologischen 

Forschung. Helvetica phys. acta, vol. 26, pp. 
241-254 (1953). 



GEOPHYSICAL LABORATORY 

Washington, District of Columbia 
GEORGE W. MOREY, Acting Director 

The geologists whose advice and counsel this work they have adopted a technique 
played so important a part in the founding which, though long used in petrology, has 
of the Geophysical Laboratory and in the never been given adequate theoretical jus- 
formulation of its initial program realized tification. A statistical analysis of the rela- 
that the solution of the problems they met tion between cross-section area and relative 
in the field required methods and tech- volume promises to provide the necessary 
niques of a research laboratory. Few rock- theoretical support for the method and 
forming processes can be observed in ac- results of the modal analysis determina- 
tion, and the field geologist rarely is able tions ("The theory of thin-section analy- 
to deduce an unambiguous solution from sis"). In addition to obtaining the abun- 
only the end products of geological proc- dance data, they have extracted the feld- 
esses. With a knowledge of the behavior spars, microcline and plagioclase, from 
of the constituent minerals and rocks in many of these granites for the purpose 
the simplified laboratory processes, how- of determining their exact composition 
ever, the geologist can go to the field with ("Composition of the microcline of gran- 
new insight in his search for understand- ites" and "Anorthite content of low-tem- 
ing of the natural processes. In order that perature plagioclase"). The labor involved 
the results of the laboratory may be most in obtaining enough sufficiently pure ma- 
useful toward this end, they must be ex- terial for chemical analysis and the time 
pressed in terms of the minerals and rocks required for such an analysis necessitate 
which confront the field geologist. the use of other methods. Methods based 

The present work of the Geophysical on optical properties ("Indices of refraction 

Laboratory is aimed primarily at the un- of natural plagioclase") and the X-ray dif- 

derstanding of the six major mineral fraction properties ("Lattice parameters of 

groups which make up the most common the sodic plagioclases") have proved suffi- 

rocks : the feldspars, quartz, pyroxenes, am- ciently accurate and precise to determine 

phiboles, micas, and olivines. Perhaps the the composition and kind of plagioclase 

most common rock on the surface of the feldspar. 

earth is granite, which contains members With knowledge from previous cursory 

of all but the last named of these major studies of the composition, kind, and abun- 

mineral groups. The first step in unravel- dance of the minerals in granite, Bowen 

ing the processes which yield granitic rock and Tuttle chose the simplest system repre- 

is to determine the composition, kind, and sentative of granite for study from the 

abundance of the constituent minerals in standpoint of synthesis. The results of 

granites from various parts of the world, more than five years' work on the system 

This work is being undertaken by Chayes quartz — soda feldspar — potash feldspar are 

and Robbins, who have assembled a large now being prepared for publication. Many 

collection of granites for which they are of the major conclusions from their study 

finding the abundance of the various con- and the companion investigations relating 

stituent minerals ("Modal analysis"). For to the general problem have been presented 

39 



4 o CARNEGIE INSTITUTION OF WASHINGTON 

in previous annual reports. There still re- These investigators determined the liqui- 

main several parts of this work, however, dus relations in the system, but the work 

to be reported now. These include the na- on mixtures of high potash content was 

ture of the "Residual solutions of a granite impeded by the volatilization of potash, 

magma" and quantitative data on the pres- and it was difficult or impossible to identify 

sures and temperatures at which natural the phases in the solidus region by optical 

granites melt ("Beginning of melting of methods. The loss of potash still presents 

some natural granites") . a technical problem, but Tuttle and Smith 

With the information gained from the have now been able to unravel the compli- 

synthetic and natural feldspar studies as cated relations in the solidus region by 

well as those on the inversion character- X-ray techniques ("The system KAlSiCX — 

istics of quartz, it was found possible to NaAlSi0 4 "). 

establish tests of the two most probable The studies outlined above deal mainly 

origins of granite. One process which may with the origin of the alkaline rocks from 

lead to the production of granite is the alkaline magmas; yet the question remains, 

metamorphism of sediments; the other is Where do the alkaline magmas come 

the crystallization of a magma. Both proc- from ? The field evidence has led most 

esses may take place, but until now no geologists to the opinion that a primordial 

quantitative criteria were available to de- magma of basic composition exists from 

termine whether a granite was of mag- which most other magmas arise through 

matic or metamorphic origin. One clue to fractionation. This process has been dem- 

the origin of a granite is to be found in onstrated many times in principle by sim- 

the temperature of the high-low inversion pie systems; the skeptical geologist, how- 

of quartz, which varies inversely as the ever, still asks for proof of its reality in 

temperature of formation; the other clue is terms of the complex natural system of 

to be found in the kind and composition many components. One step closer to re- 

of the feldspars, which also depend on the ality has been taken by Schairer with his 

temperature of their formation. Tuttle and work on the system K 2 0— MgO — AI2O3— 

Keith subjected a granite to these tests Si0 2 . Here further evidence is found that 

and found it to be of high-temperature the end product of fractional crystallization 

origin ("Magmatic versus metamorphic is a granite magma even though the parent 

origin of granite"). magma may be quite basic in composi- 

Closely related to the granites are a large tion ("The system K2O — MgO — AI2O3 — 

group of rocks called syenites which are Si02") . This is true even if these "simpli- 

especially rich in alkalies. Of particular fied magmas" are contaminated by the as- 

interest are the nepheline syenites, which similation of xenoliths of basic rocks, such 

are well represented by the system neph- as peridotites or dunites, or of highly alu- 

eline — kaliophilite — soda feldspar — potash minous sediments. Conversely, this work 

feldspar. The first steps in the investiga- demonstrates that the first liquid formed 

tion of these rocks were taken many years from a wide range of compositions is gra- 

ago and culminated with the work of nitic. This has long been the supposition 

Schairer and Bowen (1935, No. 881 1 ). of those geologists who believe some mag- 

, ... 1^, mas arise from the remelting of sediments. 

1 Geophysical Laboratory paper number. Other . . t 

Laboratory papers will be similarly referred to Such studies ° f anhydrous systems not 

by number throughout this report. only pertain to "simplified magmas," but 



GEOPHYSICAL LABORATORY a T 

also are the basis for fundamental studies models to illustrate the relations in some 

of the metamorphic rocks. The addition of simple cases in binary systems. These 

volatile components, mainly water, brings guides are useful, but, if future experi- 

us very close to the natural chemical and mental work with systems containing vola- 

physical environments of metamorphism. tile components is to meet with success, a 

Progress in the important field of the effect far more ambitious program must be un- 

of water in the formation of both the dertaken. 

igneous and the metamorphic rocks has Some experimentation by Morey has 
lagged behind that in the anhydrous sys- been aimed directly at the development of 
terns. One reason is that the obtaining of a suitable theory for volatiles. The sys- 
water pressures in experimental bombs of terns chosen involve some of the important 
the order of magnitude of those which oxides of the earth's crust. For example, 
might be found in natural rock-forming a simple system ("The system H 2 — 
processes was not possible until Morey de- Na 2 — Si0 2 ") was investigated by Morey 
veloped the method of building up pres- and Hesselgesser because the temperatures 
sure by the use of an injection pump and pressures of the critical phenomena 
(Year Book No. 40, 1940-1941). This not were within a range readily accessible with 
only enables pressures to be developed the available equipment. It was found pos- 
equivalent to the weight of ten or more sible to fix by analysis the composition of 
miles of rock, but also enables those pres- the three coexisting phases — solid, gas, and 
sures to be measured and held constant by liquid — and to demonstrate that under the 
suitable devices. Apparatus based on this high pressures used (2500 bars) the gaseous 
method has been developed by Tuttle water might dissolve as much as 33 per 
(1948, No. 1 105), and by Morey and Hes- cent of sodium silicate. Such information 
selgesser (1951, No. 1159; 1952, No. 1187). is of paramount importance to the devel- 
With accelerating experimental progress in opment of an operational theory, 
this field the theoretical treatment of sys- Other studies by Morey have dealt with 
terns involving a volatile component be- systems containing water and numerous 
comes of increasing importance. Much of inorganic salts. In one group studied, the 
this theory is based on the works of the solubility curve is continuous from ordi- 
brilliant American physicist }. Willard nary temperatures up to the melting points 
Gibbs and his distinguished Dutch dis- of the salts, and points on the pressure- 
ciple }. D. van der Waals, and is complex temperature curves of saturated solutions of 
and little understood. The application of such salts have been determined ("Three- 
the thermodynamic principles evolved by phase pressures in systems containing 
them has been mainly to organic systems, water and a salt"). In one of these, 
which differ radically from those which NaP0 3 , the entire solubility curve has 
must be considered in geological proc- been worked out ("The system H2O — 
esses. The simplifying assumptions made NaP0 3 "). In other salts the pressure- 
in the organic systems are not justified in temperature curve intersects the critical 
the water — silicate systems, chiefly because curve, and there is a temperature interval 
of the much greater difference in volatility, in which a liquid phase is not possible. 
It is therefore necessary to approach the Several such salts have been studied at 
theoretical problem from a new point of temperatures above the critical temperature 
view. Such a treatment has been started of water and at high pressures, and have 
by Morey, who has constructed solid given puzzling results. 



a 2 CARNEGIE INSTITUTION OF WASHINGTON 

The compound sodium disilicate which studied in great detail, the pressure-tem- 
appears in the system H 2 — Na 2 — Si0 2 perature relations of the various poly- 
exhibits complex polymorphism. This aux- morphs are still not well known. Two 
iliary problem has fascinated other mem- important advances in our knowledge are 
bers of the staff. Kracek, Morey, and the study by Yoder (1950, No. 1137) of 
England have established the relations the change in the temperature of the high- 
among the eleven forms and subforms, low quartz inversion with pressures up to 
and Kracek has determined some of the 10,000 bars, and a study by Tuttle and 
thermal relations ("Polymorphism of so- England of the "High-quartz-tridymite 
dium disilicate, Na 2 Si 2 Oo" and "Thermo- inversion" up to 1000 kilograms per square 
chemistry of Na 2 Si 2 5 "). centimeter. In conjunction with these 

There are other volatile constituents be- studies of the various polymorphs of silica, 

sides water, such as carbon dioxide, the Smith obtained more accurate data on the 

halogens (especially fluorine and chlorine), "Cell dimensions of tridymite and cristo- 

boric oxide, and sulfur, which are fre- balite." As will be seen in subsequent 

quently the agents of ore formation. The discussions as well, the services of an 

volatile components are probably the de- X-ray crystallographer are indispensable 

termining factor in the transport of ma- to the modern approach to mineralogical 

terial through the medium of solubility of problems. 

solid substances in the gaseous phase. Con- The pyroxene group of minerals was 
firmatory evidence of gaseous solubility of tackled in the past by means of studies on 
solid materials has recently been obtained binary joins relating most members of 
by Morey in experiments where under the group : enstatite — f errosilite, diopside — 
some circumstances the superheated steam hedenbergite, jadeite — acmite, jadeite — di- 
at high pressure has dissolved almost its opside, and others. The heart of the py- 
own weight of solid material ("Solubility roxene problem lies in a study of the 
in superheated steam at high pressures"), system enstatite — ferrosilite — hedenberg- 
In other experiments the superheated steam ite — diopside. Here may be found the 
contained 7 per cent by weight of C0 2 , complex unmixing relations so often ob- 
under a total pressure of 15,000 pounds served in the igneous rocks. This is a 
per square inch, at 400°, 500°, and 600 ° C. tedious, long-term project from which the 
In some cases, for instance with Sn0 2 and reward to be expected is as great as that 
Fe 2 3 , the C0 2 greatly increased the solu- already obtained for the feldspar studies, 
bility of solid in the gas; in other cases the Yoder's work on "Jadeite" and Schairer's 
solubility was decreased, for instance with on the systems Na 2 — FeO — Si0 2 and 
Si0 2 ("Solubility in superheated steam Na 2 — MgO — Si0 2 (see below) are con- 
containing C0 2 "). Such experiments, tributions to this problem, 
which are indispensable for the evolution The amphiboles are an even more com- 
of the theory, could become of great value plex group than the pyroxenes, mainly be- 
in the field of ore deposition. cause they contain water. It has been only 

In addition to the feldspar group, which within recent years that success has been 

plays the leading role in granite and most achieved in the synthesis of some of these 

other rocks, there remain the major groups minerals. Bowen and Tuttle (1949, No. 

quartz, pyroxene, amphibole, mica, and mi) first obtained anthophyllite under 

olivine. Although silica is the most abun- what they believed to be metastable condi- 

dant constituent of the crust and has been tions; the suggestion was offered, however, 



GEOPHYSICAL LABORATORY 43 

that anthophyllite might be stable in the AI2O3 — S1O2 — H 2 system (Yoder, 1952, 
water-deficient region (see also Yoder, No. 1199). With this foundation of ex- 
1952, No. 1 199). Support for this sugges- perimental data and technique available, 
tion was found by Tuttle and England Yoder and Eugster felt it was timely to 
("Stability relations of the amphiboles") . tackle the five-component system involving 
Tremolite and riebeckite have also been a volatile constituent, K2O — MgO — AI2O3 
synthesized, but their connection with the — Si0 2 — H 2 0, in which most of the corn- 
related pyroxenes, diopside and acmite re- mon micas appear. In addition, with some 
spectively, is not clear. It would be desir- disregard for our customary systematic ap- 
able to place more emphasis on the amphi- proach to complicated mineral groups, ex- 
boles in the near future, since they repre- ploratory runs were found to be feasible 
sent the largest gap in our knowledge of on those micas involving six component 
the rock-forming minerals. Such a hydro- oxides ("Phase relations in the micas"), 
thermal program must be preceded by a Throughout the work on the synthetic 
study of the anhydrous silicate systems micas, continual assistance was gained 
involved, and that work, though under from studies with Smith on single crystals 
way, is proceeding slowly. The work of of the natural micas ("The mica poly- 
Schairer, Yoder, and Keene on "The sys- morphs"). 

terns Na 2 — FeO — Si0 2 and Na 2 — The sixth major mineral group, the 

MgO — Si0 2 " is important for the amphi- olivines, has been studied carefully before, 

boles as well as for the pyroxenes. This year, Yoder developed a method for 

The micas have not been studied here- rapidly determining the composition of an 

tofore in as great detail as the other major olivine by means of X-ray diffraction 

mineral groups because the nature of many ("Olivine"), which will greatly aid the 

of their occurrences prevents easy separa- field geologist, for example in tracing the 

tion from the containing rocks, their chem- change of composition of olivine in a se- 

ical composition is complicated, and they quence of olivine basalt flows, 

have not yielded to previous attempts at Although the building blocks of the 

experimental investigation. Their ubiqui- geologist are the minerals in the above 

tous occurrence makes them of consider- major groups, there are other minerals of 

able importance in studies of all rock types interest for their contribution to specific 

— igneous, metamorphic, and sedimentary, theoretical problems. One of these is the 

Members of the mica group are found un- zeolite called analcite. A new theory re- 

der the entire range of geological condi- garding the nature of the interior of the 

tions : in lavas, sediments, marbles, and earth requires a transitional layer at depths 

granites; in veins and alteration zones; from 200 to 900 kilometers, between the 

and as weathering products. An investi- subcrust and a uniform homogeneous 

gation of their individual properties and mantle. It has been suggested that this 

stability conditions was considered, there- transitional layer may result from the 

fore, of great importance. The preliminary gradual change to high-pressure modifica- 

work leading to the present investigation tions of the constituent silicates. Although 

of the mica group began many years ago many simple compounds exhibit poly- 

at the Laboratory and culminated with morphic modifications at high pressures, 

the completion of the system K 2 — MgO none has previously been found in those 

— AI2O3 — Si0 2 (Schairer, 1952, unpub- rock-forming minerals investigated under 

lished) and the studies in the MgO— pressures up to 50,000 atmospheres. This 



44 



CARNEGIE INSTITUTION OF WASHINGTON 



pressure is equivalent to about 200 kilo- Laboratory undertake to provide all the 
meters depth. Failure to find the required data required for thermodynamic calcula- 
transitions was considered to be due either tions of interest to the geologist. Kracek 
to their being at pressures higher than and his colleagues have built up the back- 
those attained experimentally as suggested ground of information required for the 
by the theory, or, as investigators who op- heat-of-formation measurements ("Ther- 
pose this theory prefer, to their nonex- mochemical properties of minerals"), and 
istence. Yoder and Charles E. Weir, how- have data on some important minerals, but 
ever, have found such a high-pressure much remains to be done, 
polymorphic transition in analcite ("High- Just as thermodynamics contributes to 
pressure behavior of analcite"). our understanding of the stability relations 
The data on analcite were obtained be- of minerals, so do crystal-structure studies, 
cause of their bearing on another problem The physical laws governing the interac- 
of fundamental importance. It is desir- tion of atoms are most complicated even 
able to calculate the stability range of for simple gases. Considerable progress has 
minerals, particularly those which have de- been made in the mathematical theory of 
fled synthesis, from their thermodynamic simple ionic crystals such as the alkali 
properties. To date, only one such calcu- halides, but the theory for silicates, whose 
lation of geologic interest has been made, structures are very complex, is in a rela- 
that for the reaction 2 jadeite <=^ nepheline tively crude state. It is based on the hy- 
+ albite. A closely analogous reaction, 2 pothesis that ions are rigid spheres which 
analcite ^ nepheline + albite + 2 water, arrange themselves so that the electrical 
has been accomplished experimentally and charge in any region tends to reach a mini- 
the equilibrium curve determined (Yoder, mal value. The application of wave me- 
1950, No. 1 123). If the thermodynamic chanics gives a first approximation to an 
properties of analcite were known, in addi- accurate theory of structural energy, and it 
tion to those already obtained for the other is theoretically possible to calculate values 
participating phases, the equilibrium curve for the crystal energy solely from a knowl- 
could be calculated for the second reaction, edge of the number and kinds of atoms in 
The calculated curve could then be com- the structure. From this knowledge of the 
pared with the experimentally determined crystal energy, the stability of minerals 
curve and an evaluation made of the prob- could be deduced. Such information is es- 
able error in thermodynamic calculations sential in explaining the natural crystalliza- 
involving rock-forming minerals. Such cal- tion of minerals in terms of the simple 
culations require knowledge of the entropy physical laws governing the interaction of 
and volume changes taking place in the atoms. This very difficult mathematical 
reaction, and this in turn requires knowl- program should be complemented by an 
edge of heats of reaction, specific heat, experimental program to guide and check 
specific volumes, thermal expansions, and the mathematical results. An essential part 
compressibilities. The scope of the pro- of such an experimental program is the ac- 
gram of the Laboratory at present does curate X-ray measurement of atomic posi- 
not enable us to supply all this needed in- tions in minerals, for crystal energy is a 
formation, which must be obtained, when function of atomic positions. Smith has 
possible, from other sources which often made such accurate measurements on para- 
are not concerned with geological ma- celsian and high-carnegieite ("Significance 
terials. It is fitting, therefore, that this of the silicon-oxygen and aluminum-oxy- 



GEOPHYSICAL LABORATORY 



45 



gen distances in paracelsian and high- 
carnegieite") and has determined the struc- 
tures of these minerals ("The crystal struc- 
ture of paracelsian" and "The crystal 
structure of high-carnegieite"). 

Much of the above-mentioned work has 
centered on a specific mineral or mineral 
group. Two other very significant pro- 
grams of the Laboratory deal with several 
associated minerals or rocks in general. 
One of these is the occurrence of trace ele- 
ments, those elements present in amounts 
less than o.oi weight per cent. Here again 
the experimenter (Eugster) has been in- 
terested not merely in the accumulation 
of fundamental data, but in the applica- 
tion of these data to specific geological 
problems. He studied the "Trace elements 
in some metamorphic rocks" and found 
that the particular geological environment 
was clearly reflected in their distribution. 
The key minor elements which provide 
clues to the nature of geological processes 
can be studied from an experimental point 
of view, and the feasibility of such a study 
is now being determined. It is proposed 
that certain minor elements be added to ex- 
perimentally known mineral systems with 
the purpose of determining the quantita- 
tive distribution of those minor elements 
in the various mineral phases and in the 
liquid in equilibrium with them. 

The second program in this category per- 
tains to the problem of determining the 



"Age of rocks." The approach requires the 
extraction of a suitable mineral from the 
rock, the separation of certain radioactive 
elements from the mineral, and the meas- 
urement of the relative amounts of specific 
isotopes of these elements. From knowl- 
edge of the rate at which one isotope is 
produced from another, an estimate of the 
age of the mineral can be made. Six 
methods requiring the measurement of ten 
isotopes are known, but their applicability 
and reliability are still to be determined. 
The first step is the development and im- 
provement of the methods; the second, a 
comparative test of their reliability. Con- 
siderable effort and a large number of 
special skills are required in the execution 
of this program. Although there is some 
doubt whether such age measurements 
will be put on a push-button basis, the 
need for testing the reliability of the known 
methods more than justifies the man-hours 
expended. There is every hope that new 
techniques will be found which will permit 
the rapid determination of the age of a 
rock, particularly for those rocks devoid of 
a fossil record. 

Other studies which have been under- 
taken this year are prerequisite to future 
studies or are dividends from major efforts. 
These are added to the detailed discussions 
of the year's work, which follow in the 
order of their presentation above. 



FELDSPARS, GRANITES, AND RELATED STUDIES 



Modal analysis (Chayes, Robbins). Dur- 
ing the summer of 1952, Chayes was able 
to study and collect from some of the bet- 
ter-known granite masses of Scotland, 
Devon, Cornwall, western Normandy, and 
eastern Brittany. Robbins made a brief 
field study of the Pre-Cambrian granites 
of Missouri. Thin sections of all material 
collected during 1952-1953 have been pre- 



pared by an improved procedure which 
yields slides of so greatly improved quality 
that approximately double the former area 
is now available for measurement. 

The theory of thin-section analysis 
(Chayes). The geometrical relation be- 
tween area and volume, which is funda- 
mental in all the modern techniques for 
thin-section analysis, seems to have received 



4 6 



CARNEGIE INSTITUTION OF WASHINGTON 



little further attention — in the earth sci- indicate that this fraction should have 

ences, at any rate — since the use of area been 20 to 40 per cent microcline, only 

as a measure of volume was first suggested three of our concentrates weighed more 

by A. Delesse in 1849. Delesse was aware than 1.5 gm, and less than a third of them 

that his geometrical rationalization was weighed more than 1 gm. In every case, 

inadequate, and presented it with appro- however, despite the rather fine grain of 

priate reservations. His demonstration, many of the rocks and the characteris- 

he says, applies only to rocks which are tically interstitial habit of microcline in 

"homogeneous" in the sense that each of most of them, we were able to obtain at 

the minerals contained is "uniformly par- least 0.1 gm of material of suitable purity, 

titioned and equally developed in all direc- Difficulty in obtaining concentrates of 

tions." sufficient purity to be worth detailed study 

It may be shown, however, that Delesse' is probably the major obstacle to research 
method is perfectly general and that esti- on the mineralogy of plutonic rocks, and 
mates of relative volume based on measure- in all work of this sort methods which will 
ments of relative area are not subject to yield good results on small samples are 
bias from variations in grain size, shape, therefore at a premium. (For instance, in 
orientation, or distribution. Each of these a recently published study on the plagio- 
factors may influence the precision of a clase of plutonic rocks, Emmons and co- 
result; none affects its accuracy. Chayes workers report that they examined more 
has prepared the full argument for pub- than 300 specimens, of which only 30 
lication. yielded concentrates of sufficient purity 

Composition of the microcline of gran- and bulk.) 
ites (Chayes, Robbins). We now have on A small portion of each microcline con- 
hand more than 50 heavy-liquid concen- centrate was etched, stained, and counted, 
trates of microcline from two-feldspar If the count indicated a microcline content 
granites, and a half dozen micro- and cryp- of more than 95 per cent, the concentrate 
toperthites from alkali-granites. The aver- was accepted. Materials assaying less than 
age purity of the concentrates is about 98 95 per cent microcline were recleaned and 
per cent, with only 12 running less than 97 reanalyzed. About half the specimens 
per cent. The principal impurities are were accepted on the first count. A single 
plagioclase and quartz. After a little prac- recleaning brought most of the rest above 
tice, we found that the specific gravity the mark, but some required five or six 
of the liquid (bromoform diluted with cleanings. 

benzene) could easily be maintained with- Anorthite content of low-temperature 

in the prescribed limits for intervals suffi- plagioclase (Chayes, Robbins). As plagio- 

cient to permit the use of ordinary settling clase is one of the principal impurities in 

tubes, and that if the powder was thor- the concentrates, proper interpretation of 

oughly deslimed before treatment the set- the chemical analyses will require knowl- 

tling tubes usually produced an excellent edge of the composition of the plagioclase 

concentrate. in each sample. This information has been 

For a number of reasons we chose to obtained for about half the concentrates 

use only the 100-150-mesh fraction. Care- and should be available for the remainder 

ful stage crushing of a sample of 40 gm by the end of the coming report year, 

usually yields about 10 gm of powder in Since the anorthite content of our plagio- 

this size. Although our modal analyses clase rarely exceeds 30 per cent, the method 



GEOPHYSICAL LABORATORY 



47 



of identification proposed by Tuttle and 
Bowen (1950, No. 1133) is applicable. 

In this connection we have redetermined 
the relation between the 20(i3i)-20(i3i) 
spacing and composition, using the orig- 
inal material plus several new specimens 
prepared by Emmons and co-workers and 
kindly made available to us by the U. S. 
Geological Survey. As a result of experi- 
ence with similar curve fitting for refrac- 
tive indices (discussed below), we in- 
cluded in the computations only samples 



same specimens as above, we found for 
this new spacing that An = 59.96 ( A2© ) — 
62.31. Residual variance was again ex- 
traordinarily small (r= 0.9994). The total 
range of A2O in the new procedure is 
slightly less than in the old, and as the 
precision of the X-ray measurement is un- 
changed (except, of course, in the region 
in which the Bowen-Tuttle spacing is ob- 
scured), the sensitivity of the new pro- 
cedure must be somewhat less. But the 
difference is slight, and for practical pur- 



40i- 




40 


" 










35 












30 


- 










25 


- 










c 
< 










/ ■ 


*5 20 


- 










15 








m / 




10 






■ J 






5 


- 


*■! 


1 


1 


1 1 1 1 1 1 



1.2 



1.3 1.4 

A 29 



1.8 



(24I)-(T32) 



Fig. 1. Variation of A2© (131) _ (1 3 1) with anor- Fig. 2. Variation of A2© 



(241)-(132) 



thite content in low-temperature plagioclase. 

in which the weight percentages of anor- 
thite and albite calculated from the CaO 
and Na 2 of the analyses were such that 
1 100— (An + Ab)|<5. For these speci- 
mens the regression of composition on 
spacing is An = 51. 45 (A2O) =54.60, and, 
as may be seen in figure 1, variation unac- 
counted for by the fitted line is very small 
( r = 0.9997). 

The 20 ( i3i)-20(i3i) spacing has always 
yielded inferior results in the region 5< 
An<i2. In the next section but one of 
this report, Smith gives an explanation of 
this difficulty. He has also suggested that 
the difficulty might be avoided by using 
the 20( 2 4i)-20(i32) spacing. Using the 



with anor- 
thite content in low-temperature plagioclase. 

poses the methods are interchangeable. 
Figure 2 shows the data and regression 
line for the 20(24i)-20(l32) spacing. 

The anorthite values used in both sets 
of computations, incidentally, were calcu- 
lated directly from the lime content listed 
in each analysis; if the constants on the 
right side of each equation are divided by 
4.98, the "An" of the left side may be re- 
placed by "CaO." 

Indices of refraction of natural plagio- 
clase (Chayes). A determinative chart for 
the index-composition relation in this im- 
portant mineral series appeared in 1952 
(No. 1 177). Shortly thereafter many new 
measurements were published by Emmons 



4 8 



CARNEGIE INSTITUTION OF WASHINGTON 



and co-workers at the University of Wis- 
consin in a Memoir of the Geological So- 
ciety of America. 

The 30 new paired index-composition 
determinations presented by the Wisconsin 
group increase by almost 50 per cent the 
amount of such information accumulated 
since the birth of optical crystallography. 
It is a matter of considerable importance, 
therefore, to compare the new determina- 
tions with a chart based entirely on old 
ones. Lack of symmetry in the number of 
replications in the two sets of observations 
complicates the calculations and limits in- 
terpretation of their results. Only a bare 
sketch of the argument and its major con- 
clusions will be presented here. 

For each of the 30 specimens described 
by Emmons, an estimate of anorthite con- 
tent (An c ) may be calculated from the 
chemical analyses. These An c values re- 
flect all errors and inadequacies in chem- 
ical analysis, sample purification, and cal- 
culation procedure. For each index deter- 
mination recorded by Emmons an estimate 
of anorthite was drawn from the deter- 
minative chart, and the average of such 
estimates for each crystal (Ann) was com- 
pared with An c , as shown in figure 3. If 
Ann and An e were entirely free of error 
and were actually estimating the same 
parameter, all the points in the figure 
would lie on a straight line of unit slope 
and zero intercept. As neither estimate is 
errorless, none of these three conditions is 
likely to be satisfied exactly. The problem 
is to determine whether the observed de- 
partures are large enough to indicate the 
existence of significant differences between 
the methods. 

As the chemical analyses were not done 
in replicate, a large residual variance, 
which would be reflected by considerable 
scatter of the points about the line, would 
be virtually uninterpretable. Fortunately 



the residual variance is trifling. Similarly, 
the observed slope, 1.011, differs very little 
from unity, and by the appropriate test 
this difference fails of significance. 

The observed intercept, however, is 2.62, 
which is significantly larger than the theo- 
retical value (zero). For the refractive in- 
dices measured by the Wisconsin group, 
our determinative chart indicates anorthite 
values consistently lower than those calcu- 
lated from the Wisconsin chemical analy- 
ses. The difference is hardly large enough 



80 


- 


















70 


- 


















60 










O 










50 
c 
< 










°S 










40 




















30 




















20 


- 


















10 


- 


















*tt 


P 


1 


1 


1 


1 1 


1 


1 


1 


| 


s 




10 


20 


30 


40 50 

An S 


60 


70 


80 


90 



Fig. 3. Comparison of An fi with An c ; Emmons 
data. 

to be of practical concern, but it is of con- 
siderable theoretical interest; the case is 
an almost ideal illustration of systematic 
bias. What evidence we have suggests that 
the bias is located in the new index meas- 
urements rather than in the chemical anal- 
yses or the determinative chart. Only two 
of the specimens used by the Wisconsin 
group are from plagioclase occurrences 
which have been closely studied by other 
mineralogists, but these two, Amelia albite 
and Bakersville oligoclase, are world fa- 
mous. Records compiled in connection 
with development of the determinative 
chart contain no less than seven sets of 
measurements for Amelia and Rvt for 



GEOPHYSICAL LABORATORY 



49 



Bakersville. Unless the eleven crystallog- 
raphers responsible for these measurements 
are wrong, the Wisconsin values for the 
refractive indices of Amelia and Bakers- 
ville are decidedly low. 

Lattice parameters of the so die plagio- 
clases (Smith). As a first step to measur- 
ing the lattice parameters of all plagio- 
clases, the parameters of the more abun- 
dant sodic plagioclases are being measured. 
Tuttle and Bowen (1950, No. 1133) have 
plotted 20(i32)-20 ( i3i) against composi- 
tion and demonstrated the presence of a 
high- and low-temperature series. These 
plagioclases are triclinic with six param- 
eters, and in this study all six parameters 
are being measured, instead of the one pa- 
rameter measured by Tuttle and Bowen. 
Selected natural materials, supplied by 
Tuttle, have been measured. Prolonged 
heating near the melting point (carried 
out by Schairer) converted them into the 
high-temperature form, whose parameters 
have also been measured. Preliminary re- 
sults fully confirm the variations found by 
Tuttle and Bowen. There appears to be a 
discontinuity near An 3 5 which confirms 
the X-ray and optical evidence. One of the 
triclinic angles (y # ) passes through 90° 
near AnioAb 90 in the low-temperature 
form. Measurements on material only par- 
tially converted from the low into the 
high form show that there is a contin- 
uous change in the crystal structure. A 
natural plagioclase of composition near 
An 2 2 has lattice parameters consistent with 
a position halfway between the high- and 
low-temperature forms. Another one, of 
composition An3o, again has parameters 
consistent with an intermediate position. 
Further measurements on similar plagio- 
clases should throw light on their thermal 
history. 

Chayes has used the Tuttle and Bowen 
method to measure the composition of 
natural plagioclase. Accurate indexing of 



the X-ray patterns shows that the (132) 
reflection of Bowen and Tuttle should be 
(131). Chayes had difficulty in measuring 
the (131) reflection for compositions near 
Anio. Examination of accurately indexed 
X-ray patterns shows that the (131) peak 
is only partially resolved at these composi- 
tions from the peak (222). At An the 
(222) peak is almost coincident with the 

(131) peak, and at Ani 5 it has moved suffi- 
ciently far away to eliminate confusion. 
Examination of the accurately indexed X- 
ray patterns suggested the use of the peaks 

(132) and (241), which has eliminated the 
difficulty. 

Residual solutions of a granite magma 
(Tuttle, Bowen). The prevalent view con- 
cerning the nature of residual solutions of 
crystallizing granite magmas is that a hia- 
tus exists between magmatic liquids and 
hydrothermal solutions. Granitic magmas 
containing water and other volatiles will 
tend to concentrate these constituents dur- 
ing crystallization because they are not 
taken up by phases crystallizing early from 
the magma. The average granite has less 
than 10 per cent of minerals which contain 
water. For example, if a granitic magma 
contained 4.5 per cent water at the outset, 
the magma would consist of 50 per cent 
water when 88 per cent of the liquid crys- 
tallized. Although the solubility of feld- 
spars and quartz is small, there are certain 
silicates, such as potassium tetrasilicate, di- 
silicate, and metasilicate, which exhibit con- 
tinuous solubility with water. Such com- 
positions would appear far removed from 
the liquids to be expected from a crystal- 
lizing granite magma; proof of their re- 
ality, however, lies in the rocks themselves. 
A compilation of the norms of rhyolites 
shows that 5.4 per cent of those analyzed 
have sodium and potassium metasilicates. 
On the other hand, less than 1 per cent 
of the granites which cooled slowly and 
produced residual liquids show normative 



50 



CARNEGIE INSTITUTION OF WASHINGTON 



metasilicates. There is good reason to be- 
lieve, then, that a complete gradation of 
liquids exists from a magma to a hydro- 
thermal solution. 

Beginning of melting of some natural 
granites (Tuttle, Bowen). The beginning 
of melting for synthetic mixtures having 



1000 



ported by Greig, Shepherd, and Merwin 
(Year Book No. 30, 1930-1931). They ob- 
served that a dry granite became half liq- 
uid in one week at 800 ° C. A plausible 
explanation of this difference is that the 
dry granite melted metastably because the 
crystalline phases present were unstable at 




600 



1000 



2000 3000 

Pressure Kg /cm 2 



4000 



Fig. 4. Curves showing melting behavior of two natural granites together with the ternary minimum 



compositions closely approaching those of 
the average granite has been determined. 
In order to gain some knowledge of the 
effect of other possible constituents not 
present in the synthetic system, the melt- 
ing behaviors of two natural granites were 
studied. The results are shown in figure 4. 
If the curve is projected to zero water 
vapor pressure, anhydrous granites will be- 
gin to melt at about 950°. This tempera- 
ture is about 1 50° higher than that re- 



the temperature of the experiment. That is, 
the granite consisted essentially of quartz, 
microcline, and plagioclase, whereas the 
stable assemblage at 800 ° C would be 
quartz and sanidine. In the present work 
the primary phase of crystallization in both 
the natural granites examined is biotite. 

Magmatic versus metamorphic origin of 
granite (Tuttle, Keith). The continuing 
controversy regarding the origin of gran- 
ite is largely the result of conflicting field 



GEOPHYSICAL LABORATORY 



51 



evidence. The present state of the prob- In order to test these tools a young gran- 

lem is testimony to the inadequacy of field ite was required which had been quickly 

relations alone as a source of decisive evi- cooled and which had not suffered subse- 

dence for determining whether a particu- quent recrystallization. The Beinn 



an 



++ +W ++ 




QUARTZ FROM RHYOLITE • 
QUARTZ FROM GRANITE + 



574 

INVERSION BREAK ON COOLING °C 

Fig. 5. Inversion temperature of quartz formed at high and low temperatures in similar chemical 
environments, M, granites from three localities in Maine: North Sullivan, Jonesport, and Wallace 
Cove. P, Pikes Peak granite. W , granite from Westwood, Massachusetts. S, White Silver Plume 
granite, Colorado. 



lar granite was produced by the meta- 
morphism of sediments or by the crystal- 
lization of a liquid magma. Two new 
measuring sticks have recently been devel- 
oped which can be brought to bear on this 
problem. One makes use of the variable 
inversion in quartz, and the other, the 
polymorphism of the feldspars. 



Dubhaich granite of the island of Skye 
appears to satisfy these requirements. 

It has been shown that the high-low in- 
version of quartz grown in similar chemi- 
cal environments varies inversely as the 
temperature of formation (Keith and Tut- 
tle, 1952, No. 1 183). That is, the quartz 
from a rock formed at high temperatures 



52 



CARNEGIE INSTITUTION OF WASHINGTON 



will exhibit a lower inversion temperature temperature, it is concluded that the Skye 

than quartz formed at a low temperature, granite is the result of primary crystalliza- 

if the chemical environments are similar tion from a magma. 

(fig. 5). The results of the inversion tern- The results from the second measuring 

perature measurements of the quartz from stick, the polymorphism of the feldspars, 




INVERSION BREAK ON COOLING °C 

Fig. 6. Results of inversion temperature measurements of the quartz from Skye granite 



the Skye granite are given in figure 6. 
They indicate that the quartz from the 
Skye granite is different from the quartz 
of most granites previously studied and 
resembles, in inversion characteristics, the 
quartz from rhyolites. It is generally 
agreed that rhyolites are formed at high 
temperatures from a liquid magma. There- 
fore, on the basis of the quartz inversion 



confirm the results from the study of 
quartz. The compositions of both the pot- 
ash and plagioclase feldspars were deter- 
mined by means of an X-ray method de- 
scribed by Tuttle and Bowen (1950, No. 
1 133). In addition, the optic axial angle 
(2V) for each specimen was carefully 
measured on a universal-stage microscope. 
Since 2V is known for a specific composi- 



GEOPHYSICAL LABORATORY 



53 



tion of feldspar and for each polymorph of 
that composition, the polymorph could be 
determined for the Skye granite feldspars. 

The potash feldspars showed a consider- 
able range in iV ' , but some were close to 
sanidine, the high-temperature polymorph. 
The variation in iV is attributed to the 
partial inversion to low-temperature forms. 
The plagioclase feldspar measurements fall 
on the curve for high-temperature plagio- 
clases. It is therefore concluded that the 
feldspars in the Skye granite formed at 
high temperatures. 

These studies on the minerals found in 
the Skye granite clearly point to an origin 
at high temperatures. In fact, this particu- 
lar granite appears to be a missing link be- 
tween granites and rhyolites. Of still 
greater importance is the development of 
methods which can distinguish between a 
granite formed from the metamorphism of 
a sediment and a granite crystallized from 
a magma. 

The system KAlSiOi—NaAlSiO* (Tut- 
tle, Smith). The system has been studied 
by both dry and hydrothermal methods. 
The phases found are given in table i . The 
stability relations (fig. 7) have been 
worked out in the subsolidus region em- 
bracing all compositions up to 1000 ° C. 
Phase-equilibrium relations in composi- 
tions enclosing more than 40 per cent of 



the NaAlSi0 4 molecule have been estab- 
lished only up to the liquidus. 

Perhaps the most important result of our 
study is the location of a miscibility gap be- 
tween the two phases kalsilite and low- 
nepheline, below approximately 1000 ° C. 
The composition of the coexisting phases 
in the miscibility gap has been measured 
by X-ray methods. One of the most in- 
teresting features of this unmixing was the 
rapidity of the process. For example, 
when a single phase quenched from a high 
temperature was heated in an X-ray cam- 
era at 500° C, unmixing began within five 
minutes. Accordingly, measurements on 
the top of the miscibility gap are uncertain, 
for some unmixing may have occurred 
during quenching. 

It is not surprising that kalsilite is the 
common modification of KAlSi0 4 found 
in the volcanic rocks, for this is the stable 
form in the temperature range expected in 
these rocks. The inversion temperature of 
kalsilite at atmospheric pressure is 840° C 
in pure KAlSi04 and rises rapidly with 
increasing solid solution of NaAlSi04. Kal- 
iophilite, found in ejected blocks at Monte 
Somma, Vesuvius, is apparently different 
from all the synthetic phases encountered 
in this study. 

The solidus (low-nepheline + liquid), 
the curve representing the composition of 



TABLE 1 
Phases in the KAlSi0 4 — NaAlSi0 4 system 



Symbol Composition Name 

H2 NaAlSi0 4 Low-nepheline 

H20 NaAlSi0 4 High-nepheline 

LC NaAlSi0 4 Low-carnegieite 

HC NaAlSi0 4 High-carnegieite 

HI KAlSi0 4 Kalsilite 

01 KAlSiO, "Orthorhombic" 

02 K 4 / 5 Nai/ 5 AlSi0 4 "High-orthorhombic" 

H4 K 3 / 4 Nai/ 4 AlSi0 4 "Double-nepheline" 

K KAlSi0 4 Kaliophilite 

* The cell dimensions vary with composition and temperature. 



Symmetry 



Cell dimensions (A)* 



Hexagonal 

Orthorhombic 

Triclinic? 

Cubic 

Hexagonal 

Orthorhombic 

Orthorhombic? 

Hexagonal 

Hexagonal 



a, 10.0; c, 8.4 

a, 10.2; b, 17.6; c, 8.5 

? 

a, 7.32 

a, 5.16; c, 8.71 

a, 9.1; c, 8.56 

? 

a, 20.5; c, 8.5 
a, 26.9; c, 8.5 



54 



CARNEGIE INSTITUTION OF WASHINGTON 



crystals in equilibrium with liquid, has 
been determined from 30 to 70 per cent 
NaAlSi0 4 by measuring the composition 
of low-nepheline from the lattice param- 
eters. Above 1520 ° C, a new phase, "H4," 
in equilibrium with liquid has been found, 
giving a phase boundary between (low- 



lized dry at 1150° C. Below this tempera- 
ture it is hexagonal, and above it the sym- 
metry is lowered to orthorhombic. The 
inversion is rapid and of the displacive 
type. A small heat effect was observed at 
850° C, on the differential thermal analy- 
sis apparatus. Low-nepheline made hydro- 




600- 



400- 



NaAISiO. 



KAISi0 4 

Fig. 7. Stability relations in the KAlSi0 4 — NaAlSi0 4 system. Hi, kalsilite; H2, low-nepheline; 
H2O, high-nepheline; H4, double-nepheline; Oi, orthorhombic; O2, high-orthorhombic; HC, high- 
carnegieite. 



nepheline + liquid) and ("H4" + liq- 
uid) . The stability range of this new phase 
has not yet been determined. The region 
of high potash content and high tempera- 
ture has turned out to be very complex, 
and in this region a new phase, "O2," has 
been discovered near 20 per cent NaAlSi0 4 
and 1500 ° C. 

An inversion has been found in low- 
nepheline of composition 100 per cent 
NaAlSiCX at 850 ° C, for material crystal- 



thermally at 800 ° C also shows this inver- 
sion, but at the higher temperature of ap- 
proximately iooo° C. Its lattice parameters 
are also slightly different at room tempera- 
ture, but the reason for this discrepancy 
has not yet been established. No inversion 
has so far been found in low-nepheline of 
adjacent compositions. 

Lattice parameters have been deter- 
mined for the nepheline-kalsilite solid solu- 
tions as a function of composition. The re- 



GEOPHYSICAL LABORATORY 



55 



suit for the a spacing is shown in figure 8. 
The results have proved useful in estimat- 
ing the composition of natural nepheline- 
kalsilite solid solutions. The presence of 
excess silica (albite) in solid solution ap- 
parently does not greatly influence the de- 
termination of the ratio of KAlSi0 4 to 
NaAlSiQ 4 . 



HI (2a) 



10-30- 



N 



10-20- 



10 10 — 



1000- 



9-90- 



V H4 (o /2 ) 




H2 (a) 



KAISiO, 



1:3 



NaAISiO. 



NaAISL0 o 

o o 



Fig. 8. Variation of the lattice parameter a 
with composition for the phases Hi, H2, and H4 
in the KAlSi0 4 — NaAlSi0 4 system. The change 
of a with composition for the H2 phase in the 
NaAlSi0 4 — NaAlSi 3 O g system is also shown for 
compositions having 10, 20, and 25 per cent 
NaAlSi 3 O g . 

Another interesting result of the study is 
the sharp change of slope in the lattice 
parameters a and c of low-nepheline when 
plotted against alkali ratio at room temper- 
ature. This discontinuity is at a ratio cor- 
responding to 3 sodium atoms and 1 potas- 
sium atom. There is also a break between 
90 per cent and 100 per cent NaAlSi0 4 , 
presumably related to the inversion in 
pure NaAlSi0 4 . These results can be in- 



terpreted in terms of the crystal structure 
determined by Buerger and Hamberger. 
The silicon and aluminum tetrahedra form 
a framework (like that in tridymite) with 
the alkali atoms filling holes in the frame- 
work. Three of the holes are small and 
one is large. As the sodium atom is small 
and the potassium atom large, the ideal 
structure contains 3 sodium and 1 potas- 
sium atoms. If more potassium atoms en- 
ter the lattice (with corresponding loss of 
sodium atoms), they must enter some of 
the small holes and thereby tend to force 
the lattice apart. This may explain the 
increase of lattice parameters found experi- 
mentally. If extra sodium atoms enter the 
lattice, small atoms enter large holes and 
the lattice collapses, thus giving the re- 
duced parameters found experimentally. 
When large potassium atoms enter small 
holes the lattice is forced to expand, but 
when the small sodium atoms enter large 
holes the natural rigidity of the tetrahedral 
framework partly compensates for the 
small atoms. This explains the observed 
change of gradient of lattice parameters 
versus composition. When sufficient small 
atoms enter large holes in the lattice, the 
lattice can collapse to a configuration of 
lower symmetry, a fact which affords an 
explanation of the reduction of symmetry 
only near pure NaAlSi0 4 . The substitu- 
tion of albite in pure NaAlSi0 4 stabilizes 
the lattice again, presumably because the 
extra silicon atoms change the framework 
so that the sodium atoms again fill the 
holes. 

When most of the sodium atoms in low- 
nepheline are replaced by potassium atoms, 
the slightly kinked tetrahedral framework 
straightens out to give the kalsilite struc- 
ture. This reduces the lattice parameter a 
from 10 A to 5 A, but the structure is very 
similar to that of low-nepheline. The 
"H4" structure is intermediate between 
kalsilite and low-nepheline and probably 



56 



CARNEGIE INSTITUTION OF WASHINGTON 



represents the first stage in the straighten- spinel has a ternary eutectic with leucite, 

ing out of the low-nepheline structure. At corundum, and spinel as the crystalline 

800 ° C, the break of the lattice parameter phases in equilibrium with liquid at 1543° 

with the 3:1 atom ratio in low-nepheline ±5° C at the composition leucite 88.0, 

has almost disappeared, showing that corundum 1.5, spinel 10.5 per cent by 

either (a) the holes now have the same weight. 

size, (b) the sodium and potassium atoms Quenching-run data were completed for 

have the same size, or (c) the sodium and that portion of the join leucite — forster- 

potassium atoms are disordered. It is in- ite — periclase whose liquidus temperatures 

teresting that Donnay and Donnay sug- lie below 1650° C, the practical upper limit 

gested that mechanism (b) was responsible for platinum-wound resistance furnaces, 

for the change in the monoclinic-triclinic The primary phase volumes of periclase, 

inversion with temperature in the alkali forsterite, and leucite are cut by this join, 

feldspars. but no piercing points of quaternary uni- 

The system K 2 — MgO — AI2O3 — Si0 2 variant lines lie on it. The composition 

(Schairer). The three joins leucite — for- K 2 • 6MgO ■ AI2O3 * 6Si0 2 (the mica 

sterite — spinel, leucite — corundum — spinel, phlogopite is K2O ■ 6MgO • AI2O3 * 6Si0 2 * 

and leucite — forsterite — periclase were com- 2H2O) lies on this join; and this anhy- 

pleted during the past year but have not drous composition has a forsterite liquidus 

yet been written up for publication. The at i628°±5°, forsterite crystals are joined 

first two of these joins are ternary sys- by leucite crystals at 1478^5°, and the 

terns within the quaternary system K 2 — composition begins to melt at 1428° ±5° C. 

MgO — AI2O3 — Si0 2 . The system leucite — A new join, leucite — forsterite — K 2 0* 

forsterite — spinel has a ternary eutectic AUOs^SiC^, has just been started, and 

with leucite, forsterite, and spinel as the the first three compositions are now in 

crystalline phases in equilibrium with liq- course of preparation. This join is of im- 

uid at 1463 ° ±5° at the composition leucite mediate interest to Yoder and Eugster, 

75.5, forsterite 17.5, spinel 7.0 per cent by who are studying the relations between 

weight. The system leucite — corundum — phlogopite, muscovite, and clinochlore. 



HYDROTHERMAL AND AUXILIARY STUDIES 



The system H 2 — Na 2 — Si0 2 (Morey 
and Hesselgesser) . Work on the 500° and 
600 ° isotherms in this system is complete, 
except for the high-Na 2 part. A plati- 
num-lined bomb should soon be available, 
with which we hope to extend the studies 
at 400 °, 500 °, and 600 ° C far enough to 
reach the alkali-rich boundary of the field 
of Na 2 Si0 3 . 

Numerous experiments have been made 
at the critical temperature of water, 374 ° C, 
to establish the boundaries of the first crit- 
ical end-point curve, and some additional 
work has been done at lower temperatures. 



It appears certain that both the first and 
the second critical end-point curves lie be- 
tween 374° and 400 ° and that the pressures 
at the second critical end-point curve are 
very high, greater than 3000 bars. Within 
this short temperature interval of less than 
26°, the vapor pressures of solutions in 
equilibrium with crystalline solids increase 
at least 15-fold. Moreover, other studies 
(1952, No. 1 187) indicate that this may be 
a common relationship in systems contain- 
ing water and salts of low vapor pressure. 
In addition, some experiments have been 
made at lower temperatures to tie in with 



GEOPHYSICAL LABORATORY ^ 

work of others at temperatures below equilibrium G + L + S, which, provided 

ioo° C. It is hoped to assemble all this in- no compounds are formed, goes from the 

formation in one review paper on the eutectic G + L + ice + S to the melting 

entire system from room temperature to point of the salt, is intersected by the crit- 

the melting point of some of the anhy- ical curve which joins the critical point of 

drous compounds. water with that of the salt. There must be 

Three-phase pressures in systems con- two such intersections, P and Q, giving rise 

taining water and a salt (Morey). The to a lower and an upper critical end point, 

determination of three-phase pressures gas and dividing the P-T curve into three 

+ liquid + solid in binary water-salt sys- sections. The first section is from low 

terns, that is, the vapor pressures of solu- temperatures up to the first or lower criti- 

tions saturated with the salt in question, cal end point, P; the third section is from 

has been continued, and has produced the melting point of the salt down to the 

some puzzling results. The salts studied second or upper critical end point, 0; and 

may be listed in two groups : the second section, between the two critical 

i. Salts whose solubility curve does not end points, is unstable except just adjacent 

intersect the critical curve. The solubility to the critical end points, where it is meta- 

curve is continuous up to the melting point stable. 

of the salt, and the three-phase pressure at The following salts have been found 
the critical curve of water is less than the to have a first critical end point: LiF, 
critical pressure of water. The following NaF, Li 2 S0 4 , Na 2 S0 4 , T1 2 S0 4 , Li 2 C0 3 , 
salts are included in this group : NaCl, KF, Na 2 C0 3 . Points on their three-phase 
KC1, CsCl, PbCl 2 , Na 2 0'2B 2 3 , Na 2 0* curves at 400° and 500° C have been de- 
3B2O3, Na 2 0'4B 2 3 , NaP0 3 , KP0 3 , termined for T1 2 S0 4 , Li 2 S0 4 , K 2 SC> 4 , and 
Na 4 P 2 7 , K 4 P 2 7 , K 2 C0 3 . Three-phase a point at 400° (800 bars) for Na 2 S0 4 . 
pressures in these systems have been deter- These pressures are greater than the ex- 
mined at 400 °, 500°, 600 °, and, when nee- trapolated P-T curve of water, and in each 
essary to outline the entire pressure-tem- case the slope of the P-T curve is positive, 
perature curve, at 700° C. It is difficult to reconcile these P-T curves 

2. Salts whose solubility curve intersects with the requirements of a system having 

the critical curve. The test for this condi- end points of the P-Q type. In some of 

tion is that at the critical point of water, these systems, complications arise owing to 

374° C, and under the critical pressure formation of two immiscible liquid layers, 

(221.06 bars = 3206.17 psi) or slightly a condition which gives rise to formidable 

higher (241 bars = 3500 psi), water theoretical complications. Also, solubilities 

(steam) does not melt the salt; hence the of salt in gaseous water of over 50 per cent 

vapor pressure of the saturated salt solu- have been observed. The applicable theory 

tion must be greater than that of water at is being developed, 

its critical point. The system H 2 0—NaP0 3 (Morey). To 

This is the condition for a first critical one interested in silicates, the chemistry 

end point. Probably the simplest case in of the phosphates also is of interest. In 

which there is a first critical end point both cases the structural element is a tetra- 

is that in which there is also a second hedral grouping of four oxygen atoms 

critical end point without complication around a central positive atom, and the 

from the formation of two immiscible liq- various compounds are formed by repeated 

uids. In this case, the P-T curve for the polymerization. The three-phase composi- 



58 



CARNEGIE INSTITUTION OF WASHINGTON 



tions, pressures, and temperatures have 
been determined from ioo° C up to the 
melting point of NaP0 3 (629° C). The 
solid phases are: NaH 2 P0 4 , incongruent 
melting point 169°, 4.1 bars; Na 2 H 2 P 2 C>7, 
incongruent melting point 375°, 12.5 
bars; NaP0 3 II, transition temperature to 
NaP0 3 I 443°, 15 bars. This is one of the 
few complete solubility curves of water-salt 
systems which have been determined. 

Polymorphism of sodium disilicate, 
Na 2 Si 2 5 (Kracek, Morey, England). 
From results published in earlier papers by 
this Laboratory, it has become evident that 
sodium disilicate exhibits polymorphism; 
in particular, it was found that materials 
crystallized dry had different optical prop- 
erties from those crystallized in bombs in 
the presence of water, and that the prod- 
ucts of the dry heat treatment exhibited 
two readily reversible rapid transitions. 
Further work showed different X-ray dif- 
fraction patterns for material crystallized 
under different conditions. Some of the 
different forms were found to be mutually 
convertible, with speeds of inversion de- 
pendent on the temperature. In addition, 
it was found that two of these inert forms 
have rapid, readily reversible transitions. 

The principal inert forms or phases cor- 
respond by analogy to such slowly con- 
vertible phases as the quartz, tridymite, 
and cristobalite forms of silica, or the neph- 
elite and carnegieite forms of NaAlSi0 4 . 
As such they could be given mineral 
names; but since in nature, in the presence 
of water, they would be unstable with re- 
spect to other mineral assemblages present 
in rocks, they could not properly be re- 
garded as even artificial minerals. Indeed, 
the only mineral of disilicate composition 
containing sodium listed in Dana's Text- 
boo^ of Mineralogy is rivaite, (Ca, Na 2 ) 
S12O5. 

We have given the different inert forms 
of Na 2 Si 2 5 capital-letter names, A, B, C, 



etc., A being the phase stable at the highest 
temperature. The modifications produced 
as a result of rapid reversible transitions in 
the principal phases are analogously given 
lower-case Greek-letter names combined 
with the name of the principal phase with- 
in which they occur, thus Aa, A3, etc., a 
being the high-temperature modification. 

The transformations of the principal 
forms were studied both hydrothermally 
and under dry conditions. The transfor- 
mations in the dry state were found in 
general to be more sluggish and to require 
higher temperatures for conversion than 
the hydrothermal ones. 

The relations of the various polymorphs 
are given schematically in figure 9. Phase 
A was produced by crystallizing a pow- 
dered glass of the requisite composition 
above 670 ° C. Phase B was also produced 
in the dry way within the temperature 
range 591 ° to 650° C. Hydrothermally, B 
was obtained at 430° C and 6 atm water 
vapor pressure, as well as at lower temper- 
atures and higher pressures. Phase C was 
not obtained in the dry way, but was pro- 
duced from a glass, A or B, under 1500 
and 3000 psi water vapor pressure (see 
inset in fig. 9) at temperatures near 660 ° C. 
Phase D was not obtained in the present 
experiments, but had been identified by 
Morey and Yoder in previous work. It 
was found to transform to A at 722 ° C. 
Phase E was obtained only by heating 
glass in the temperature range 500 ° to 
588 ° C. Phase F was discovered by H. S. 
Roberts in the course of work on the latent 
heats of various silicates. He observed that 
Na 2 Si 2 5 when crystallized below about 
700° always gave the two rapid transitions 
characteristic of phase A. If, however, the 
preparation was first heated above the 
melting point of A, and then crystallized 
above 706 °, it usually appeared in a new 
variety which exhibited neither of the two 
rapid transitions, and melted several de- 



GEOPHYSICAL LABORATORY 



59 



grees lower than the stable phase, with 
a higher latent heat of melting. When 
partly melted, it often refroze and then 
gave a second melting point, that of A. 
Later work has confirmed Roberts' state- 



Thermochemistry of Na 2 Si 2 5 (Kra- 
cek). Thermochemical data for sodium 
disilicate are included in table 6 with those 
for other alkali silicates to be described in 
a following section. Table 2 presents a 




600 



700 



1000 2000 3000 psi 



Fig. 9. Imaginary vapor-pressure curves for the various phases of Na 2 Si 2 5 . Solid lines represent 
stable states and dotted lines metastable states at the various temperatures t° C. The position of the 
curves indicates the relative stability of the phases or their modifications, although their actual posi- 
tions or shapes are unknown. Those for phases A, B, and E were chosen from thermochemical 
considerations; those for C, D, and F were chosen arbitrarily. The inset figure represents the results 
of experiments on the formation of phase C at the indicated pressures of water vapor. 



ments in general, and shows that F when 
cooled to room temperature yields an X-ray 
pattern similar to that of A a taken at 820°, 
but noticeably simpler. F cannot be re- 
tained long at room temperature; it inverts 
in about a day to Ay. Present data indicate 
that F is metastable with respect to A and 
monotropically related to Aa. 



more detailed analysis of the values of the 
heats of transformation and the informa- 
tion that can be derived from them con- 
cerning the stabilities of the various phases. 
It will be noted that form E has the lowest 
heat of crystallization, measured at 25 ° C, 
of the three forms studied; also that if the 
reactions would take place at 25 , E as 



6o 



CARNEGIE INSTITUTION OF WASHINGTON 



well as A would transform to B with evo- 
lution of heat, and hence that both E and 
A are metastable with respect to B at 25°. 
It is further seen that E is also metastable 
with respect to A at 25 °, and, indeed, it 
was found in the dry-heat-treatment studies 
of E that in some cases E was at least par- 
tially transformed to A, with the remain- 
der simultaneously transformed to B at 
temperatures at which A is metastable 
with respect to B. The preferential crystal- 

TABLE 2 

Thermochemistry of polymorphous forms of 
sodium disilicate 

Latent heats of phase change 
Condi- AH (sol, 74.7° C) at 25° C (kcal/mole) 

tion (kcal/mole) 

gl > x E > x A > B 

Glass.. -104.70 

-2.72 

E -101.98 

-4.66 -1.94 

A -100.04 

-5.25 -2.53 -0.59 
B - 99.45 

gl, glass; x, crystal; A, B, E, polymorphous 
forms. No measurements were made on phases 
C, D, and F. 

lization of glass to E at certain tempera- 
tures rather than to the stable B is a clear 
instance of the operation of the Ostwald 
stepwise rule for phase transitions. 

Solubility in superheated steam at high 
pressures (Morey). This work has been 
continued, and some of the results are as 
follows : 

CaCOs: Solubility at 500 C, 15,000 
psi = 12 X io -6 weight fraction. At the 
same time excess C0 2 was carried over in 
amount 9X io~ 6 . 

BeO: 400°, 15,000 psi = 24X10" 6 ; 500°, 
15,000 psi = 55 X io -6 . 

In addition, work has been done with 
germanium oxide, which shows a much 
larger solubility than quartz, and with 
uranium oxide. 



Solubility in superheated steam contain- 
ing C0 2 (Morey). Carbon dioxide was in- 
troduced into the system by saturating the 
water with CO2 under the pressure of 
liquid C0 2 at room temperature. This 
gives about 7 per cent C0 2 . Much trouble 
resulted because of the corrosive action of 
the carbonic acid on iron. The water satu- 
rated with C0 2 corroded the valves of the 
pump in a short time, and the water pass- 
ing into the bomb carried a large amount 
of ferrous carbonate. The present method 
is to fill a stainless steel cylinder one half 
with water and the other half with liquid 
CO2. This cylinder is between the pump 
and the bomb, so that the valves do not 
come into contact with the C0 2 -saturated 
water. The water, saturated with CO2 and 
under pressure, passes through a small 
bomb containing an ion-exchange resin to 
remove the last trace of iron just before it 
goes into the main bomb. These steps have 
so greatly improved the operation that it 
is desirable to repeat all previous runs. 

Following are the preliminary results for 
solubility at 500° C, 15,000 psi total pres- 
sure, with about 7 per cent C0 2 present : 

CaC0 2 : 940 X 1 o~ 6 , a more than 7-fold 
increase as the result of the presence of 

co 2 . 

Cassiterite: 50X10" 6 , an increase of 20- 
fold. 

Hematite: 230 Xio -6 , an increase of 3- 
fold. 

Quartz: 19X10" 4 , a decrease in solu- 
bility of 6 X io -4 . • 

Albite: The results are not satisfactory; 
but it appears probable that the CO2 de- 
creases both the silica and the alumina. 

It is planned to keep this program in 
active operation. More work should be 
done with inorganic oxides; the necessary 
changes should be made for working with 
more soluble salts such as K 2 SC>4, and 
also for working with molten salts, such 
as NaCl, at pressures greater than the 
three-phase pressure. 



GEOPHYSICAL LABORATORY 



61 



QUARTZ, PYROXENE, AND AMPHIBOLE GROUPS 



High-quartz-tridymite inversion (Tut- 
tle, England). Data have been obtained 
on the high-quartz-tridymite inversion up 
to iooo kg/cm 2 (fig. 10). These determi- 
nations are in disagreement with the rela- 



405 ° C (i.e., well above the high-low inver- 
sions) on the high-temperature powder 
camera. Quartz was used as the inter- 
nal standard. The results were: cristo- 
balite, cubic, = 7.1382 ±0.0010 A; tridy- 



5000 r 



4000 



3000 






2000 



1000 




500 



1000 

Temperature Degrees C 



1500 



Fig. 10. Curve showing high-quartz-tridymite inversion at pressures up to 1000 kg/cm- 



tions obtained from thermodynamic data. 
Cell dimensions of tridymite and cristo- 
balite (Smith). In view of the inaccuracy 
of the previous measurements of cell di- 
mensions, Tuttle suggested that they be 
measured accurately in order to determine 
the pressure dependence of the tridymite- 
cristobalite inversion (see fig. 10). Ac- 
cordingly, measurements were made at 



mite, hexagonal, 0=5.0463 ±0.0020 A, c — 
8.2563 ±0.0030 A; volume of cristobalite 
cell, 363.72 ±0.2 A 3 ; volume of two tridy- 
mite cells, 363.98 ±0.4 A 3 . 

At 405 ° C, therefore, the volumes for 
the same number of atoms agree within 
the experimental error, and, consequently, 
the results do not indicate the direction 
of the pressure dependence of the inver- 



6 2 CARNEGIE INSTITUTION OF WASHINGTON 

sion. They do show that the magnitude ene and quartz. This behavior indicated 

must be small. It is possible that the cell that the amphibole was unstable in the 

volumes change differentially with tern- presence of an excess of water vapor, or 

perature, but no measurements have yet that pure magnesian anthophyllite was un- 

been made. stable and small amounts of cations other 

This remarkable closeness of the cell than magnesium were necessary to stabil- 

volumes does not seem so surprising when ize the structure. Experiments have been 

the crystal structures are examined, for carried out which indicate that the first 

these differ only in the long-range struc- suggestion is more likely correct. An- 

ture. thophyllite has now been synthesized by 

]adeite (Yoder, Chesterman, Switzer). heating a charge of MgO, Si0 2 , and H 2 
The considerable interest in jadeite con- in a sealed platinum tube at about 815 C 
tinues. It is still regarded by some as an with 1000 atm external pressure. Tremo- 
important constituent of the subcrustal ma- lite has been synthesized by heating mix- 
terial, and it figures prominently in the tures of MgO, CaC0 3 , and silica glass of 
problem of the so-called high-pressure min- the appropriate composition at 400° C and 
erals. Recent reports of the synthesis of 1000 atm water vapor pressure. At 500 C 
jadeite by other laboratories have been in- and the same pressure, the mixture crystal- 
vestigated but not substantiated. The pres- lizes into talc and diopside. Riebeckite has 
ent studies consist in a detailed examina- been synthesized by England, using the 
tion of the material collected from the sealed-tube technique. The amphibole was 
recently discovered jadeite deposit of San obtained in runs in which less than 3.9 
Benito County, California. Chemical anal- per cent water was present with the tem- 
yses of four jadeites having different phys- perature below 61 o° C. If the water con- 
ical properties have been obtained. One tent and temperature were above these re- 
sample by chance has proved to be the spective values, the product was acmite. It 
purest jadeite on record. The analyzed has often been observed that the quartz- 
materials will be used in the construction perthite granites have an amphibole as the 
of a compositional determinative chart principal dark mineral and that the two- 
based on X-ray diffraction data and optical feldspar granites carry a mica. This obser- 
properties. This investigation is a co-oper- vation supports the contention that the 
ative project with Mr. C. W. Chesterman, character and amount of unmixing in the 
Division of Mines, State of California, and feldspars are controlled in part by the 
Dr. George Switzer, of the U. S. National amount of water vapor. When the amount 
Museum. of water present is in excess (indicated by 

Stability relations of the amphiboles a mica), the feldspar unmixes completely 

(Tuttle, England). The stability relations into two feldspars. When the amount of 

of the amphiboles have long been major water present is small (indicated by an 

mineralogical problems. Their experi- amphibole), the unmixing of the feldspar 

mental investigation has been tedious and is incomplete and perthite results, 

the data are few. Anthophyllite was pre- The systems Na 2 — FeO — Si0 2 and 

viously synthesized by Bowen and Tuttle Na 2 — MgO — Si0 2 (Schairer, Yoder, 

(1949, No. 1111), by decomposing talc in Keene). Data on the stability relations 

the presence of water vapor, but continued of the dry silicates at normal atmospheric 

heating under the same conditions caused pressure are the cornerstone on which 

the amphibole to break down into a pyrox- progress on the more difficult hydrous 



GEOPHYSICAL LABORATORY 



63 



systems and systems at high hydrostatic tain alkaline rocks and minor mineral 
pressures is based. Although studies of constituents of many of the igneous rocks, 
dry silicate systems have been in progress During the past year, attention has been 
at this Laboratory for the past forty-seven concentrated (Schairer, Yoder, Keene) on 
years, much remains to be learned about the ternary system Na 2 — MgO — Si0 2 . 
the fundamental relations between the im- This system has proved to be unusually 
portant rock-forming oxides. Even though complicated and interesting. So far we have 
we have been able to attack the problem recognized eight different ternary com- 
of the melting and crystallization relations pounds, all of which have incongruent 
in complex quaternary and even quinary melting points and some of which have 
systems by separating them into a series very restricted fields of stability on the 
of smaller parts and by treating each of liquidus surface. We have prepared 187 
these parts as a unit, there still remain a separate ternary compositions and studied 
few fundamental ternary systems on which them by the method of quenching. Prep- 
data are meager or entirely lacking. aration and study of such a large number 

No reliable data are available on the sys- of compositions were required to locate 
tern Na 2 — FeO — Si0 2 . Last year a re- accurately the phase boundaries of the 
connaissance of this system was begun many fields and the large number of ter- 
(Schairer, Thwaite, Yoder) which showed nary invariant points, most of which are 
it to be unusually complex and difficult ex- reaction points because of the incongruent 
perimentally. The melts were viscous and nature of the ternary compounds' melting 
failed to come to equilibrium promptly in behavior. Several of the new compounds 
iron crucibles. Many new crystalline phases are so similar in optical properties that 
were encountered whose X-ray patterns they are difficult to identify under the mi- 
were obtained but whose compositions croscope, particularly when they are pres- 
were unknown, and it was evident that ent as tiny crystals suitable for rapid at- 
some of them were metastable phases and tainment of equilibrium between crystals 
that equilibrium had not been attained, and liquid. Each of the compounds, how- 
At this stage it became obvious that further ever, gives a very characteristic X-ray pow- 
progress in the system Na 2 — FeO — Si0 2 der pattern by which it may readily be 
required a knowledge of the comparable identified. Fortunately, equilibrium be- 
system Na 2 — MgO — Si0 2 . A search of tween crystals and liquid is usually at- 
the literature revealed that this system had tained in the system in a few hours or 
been studied by Russian investigators, but days, depending on the composition. It 
a laboratory reconnaissance showed that was necessary to use crystalline material 
the Russian data were inadequate and un- for the quenching runs, and even then, in 
reliable. some cases where crystallization had not 

A knowledge of the crystalline phases taken place in the proper temperature 

and melting relations in the two ternary range, a metastable liquidus was deter- 

systems Na 2 — MgO — Si0 2 and Na 2 — mined before the stable crystalline phase 

FeO — Si0 2 is prerequisite to studies of was encountered. 

more complex hydrous systems. The lat- We present here a preliminary phase 

ter studies would elucidate the complicated diagram for the system Na 2 — MgO — 

compositions of, and relations between, the Si0 2 (fig. 11). Only the fields of the 

so-called alkaline pyroxenes and amphi- several primary phases and the ternary 

boles, which are major constituents of cer- invariant points are shown. The tempera- 



6 4 



CARNEGIE INSTITUTION OF WASHINGTON 



tures placed at the ternary invariant points in progress. This preliminary diagram is 

are only approximate, and their more pre- given at this time so that it may be useful 

cise determination is now in progress. The immediately to workers in ceramics and 

tie lines are not shown because the compo- metallurgy who require only a general 

sition of some of the ternary compounds knowledge of melting temperatures and 



/695+5°i 



Si0 2 



/695±5 
70, 



/543±2 




/557±2° 

MgOSi0 2 



2MgOSi0 2 

/890±40 a / 
40. 



q 2 0-Si0 2 



Na 2 
IA/T. PER CENT 

Fig. ii. Preliminary phase diagram for the system Na 2 — MgO — Si0 2 , showing fields of primary 
phases and the ternary invariant points (equilateral triangle truncated at about 25 per cent Si0 2 ). 

is not yet known with certainty. Experi- the compositions and approximate temper- 
ments to determine the exact composition atures of the low melting eutectics in this 
of each of the ternary compounds are now system. 



MICA GROUP 

Phase relations in the micas (Yoder, K 2 (Mg 5 Al) (Al 3 Si 5 )0 2 o(OH)4; leucophyl- 

Eugster). The following end members of lite, K(MgAl)Si 4 Oi (OH) 2 ; annite, KFe 3 - 

the mica group were investigated: mus- (AlSi 3 )Oio(OH) 2 ; paragonite, NaAl 2 - 

covite, KAl 2 (AlSi 3 )Oio(OH) 2 ; phlogo- (AlSi 3 )Oio(OH) 2 ; and polylithionite, 

pite, KMg 3 (AlSi 3 )Oi (OH) 2 ; eastonite, K(Li 2 Al)Si 4 Oi (OH) 2 . To determine 



GEOPHYSICAL LABORATORY 



65 



their mutual relations and their stability 
relative to those minerals commonly asso- 
ciated with them, the following joins were 
studied : muscovite — phlogopite, phlogo- 
pite — eastonite, muscovite — leucophyllite, 
muscovite — quartz, muscovite — clino- 

chlore, phlogopite — annite, muscovite — pa- 
ragonite, muscovite — montmorillonite. 

The unit of structure of mica consists of 
two sheets of silica tetrahedra bound by oc- 
tahedrally co-ordinated aluminum atoms. 
These double sheets are held together by 
large potassium (or sodium) atoms in 12- 
fold co-ordination. The hydroxyl groups 
occupy sites at corners of the aluminum 
octahedra. There are four tetrahedral, 
three octahedral, and one dodecahedral 
sites per unit. The mica structures are 
built of one, two, three, or six of these 
units. The stacking of these units may be 
accomplished in different ways, and it is 
this property which permits polymorphism 
in the micas. 

There are essentially two basic types of 
mica structure: one in which all the octa- 
hedral positions are filled, as in phlogopite, 
and one in which only two-thirds of the 
octahedral positions are filled, as in mus- 
covite. Complete solid solution between 
these two types is not believed possible. 
For example, the partial atomic substitu- 
tion along the join muscovite — phlogopite 
is according to the scheme 2AF 1 ^ 3Mg VI , 
where the roman numerals refer to the co- 
ordinated position. In a complete solid- 
solution series, such as that along the easto- 
nite — phlogopite join, the substitution 
wholly within one type is A1 VI A1 IV ^ 
Mg VI Si Iv . A similar substitution, but re- 
taining an unoccupied octahedral site, 
takes place along the join muscovite — leu- 
cophyllite. A third type of substitution in- 
volves the potassium atom. This may go 
according to the scheme K XII A1 IV ^ Si IV * 
H 2 O xn , as in the soil micas. The substitu- 
tions in lepidolite are: Li VI Li VI Si IV ^ 



A1 VI A1 IV as in the polylithionites, and 
Li VI Al IV <=^ Si IV as in the paucilithionites. 
Neither of these schemes permits a com- 
plete series of solid solutions between mus- 
covite and lepidolite. This finding is sup- 
ported by recent studies of natural lepid- 
olites in the Mineralogical Laboratory of 
the University of Michigan. In those sub- 
stitution schemes involving Mg +2 , the atom 
Fe +2 may proxy. Similarly, sodium may 
proxy for potassium as in paragonite. 

The chief difficulties in the experiments 
on the mica group were slow reaction 
rates, change of composition during the 
run, difficulty in identifying products, and 
formation of metastable products. The 
first difficulty was obviated through the 
construction of a sufficient amount of ade- 
quate hydrothermal equipment to permit 
continuous runs up to three months' dura- 
tion. The changes of composition during 
the run were essentially eliminated by the 
use of sealed platinum tubes. The tech- 
nique of welding small tubes containing 
the sample and water has been perfected 
to a fast, routine operation. The fine- 
grained nature and imperfect crystalliza- 
tion of the products made identification by 
the customary optical methods exception- 
ally difficult or impossible. X-ray diffrac- 
tion and, on occasion, electron diffraction 
techniques were relied on for determina- 
tion of the phases. Metastable products 
were found to persist only in specific mix- 
tures of a particular composition. By sys- 
tematically preparing all possible combina- 
tions of natural and synthetic compounds 
in the requisite proportions for each de- 
sired composition, mixtures were found 
suitable for detailed hydrothermal study. 

Muscovite: The syntheses of randomly 
stacked one-layer monoclinic muscovite 
(iMd), one-layer monoclinic muscovite 
(iM), and two-layer monoclinic muscovite 
(2M) have been accomplished. The re- 
maining known polymorph of muscovite, 



56 CARNEGIE INSTITUTION OF WASHINGTON 

three-layer rhombohedral (3R), was ob- psi. Above this curve, sanidine + corun- 

tained in only one run with 2M muscovite, dum + vapor are the stable phases. The 

and its synthesis is therefore not substan- geological implications of this curve are 

tiated. In those previous attempts to syn- many. For example, a comparison of this 

thesize muscovite for which X-ray data upper stability curve of muscovite with the 

have been published, the phase produced minimum melting curve of the granite 

is identified by this Laboratory as iM mus- system determined by Bowen and Tuttle 

covite. It is believed, therefore, that the suggests that muscovite forms in granitic 

present work includes the first synthesis of magmas above approximately 25,000 psi 

the common hydroxyl-bearing 2M musco- water vapor pressure, and in the solid state 

vite, the mica now used extensively in below that pressure in granitic rocks, 

industry. These relations may account for the ap- 

The stability ranges of the muscovite parent two generations of muscovite in 
polymorphs named could not be fixed ac- some granites. As a corollary to this rela- 
curately because of the sluggish nature of tion, muscovite should not be found in one- 
the transformations. The following trans- feldspar granites, and preliminary studies 
formations, however, were effected : iMd— » of such granites are in accord with this 
iM-^2M. The first transformation is prob- conclusion. In addition, the upper stabil- 
ably dependent on factors affecting reac- ity curve of muscovite marks the condi- 
tion rates. The second transformation may tions of the second sillimanite (or ortho- 
be related to a univariant curve of equilib- clase) isograd. This isograd usually marks 
rium (i.e., an isograd) . A natural 3R mus- the highest temperatures reached in meta- 
covite was converted to 2M after 3 months' morphism, and, therefore, outlines the re- 
hydrothermal treatment. gion of experimental conditions in which 

The randomly stacked one-layer mono- to investigate the critical isograds at lower 

clinic muscovite gives an X-ray pattern temperatures. The sequence iMd— >iM— » 

identical with that of material called illite, 2M probably obtains in the metamorphism 

a common mineral found in soils. Illite of sediments. 

has been loosely defined as a mica contain- Phlogopite: The one-layer monoclinic 

ing less potassium and more water than (iM) or the three-layer rhombohedral 

muscovite. It is proposed to redefine illite (3R) phlogopite has been synthesized, 

as a mica of muscovite composition having These forms are very difficult to distin- 

a randomly stacked one-layer monoclinic guish by means of powder X-ray diffrac- 

structure. Those micas which lie on the tion patterns, but are easily distinguished 

join illite — montmorillonite, having less from the 2M phlogopite, which has not 

potassium and more water than muscovite, been synthesized. A curve through the 

may be called hydromicas. Illite, so de- points 840° C and 1000 psi water vapor 

fined (iMd), can easily be distinguished pressure, 995 ° and 5000 psi, 1025 and 

from iM muscovite by the absence of the 10,000 psi, and 1050 ° and 15,000 psi marks 

h\l reflections in the powder X-ray difrrac- the upper limit of stability of phlogopite. 

tion pattern. Above this curve, the stable phases are 

The upper stability limits of muscovite forsterite + leucite + kalsilite + vapor, 

have been determined and are represented These same phases form metastably at 

by a curve passing through the points temperatures immediately below the curve, 

630° C and 5000 psi water vapor pressure, particularly at low pressures. 
665 ° and 15,000 psi, and 705° and 30,000 The phlogopite forms quickly at the 



GEOPHYSICAL LABORATORY 



6 7 



higher temperatures and grows very slowly eastonite — annite — siderophyllite. Recon- 

at the lower temperatures. It has not been naissance studies on the joins phlogopite — 

ascertained whether the polymorphs are eastonite and phlogopite — annite show that 

related by a univariant curve of equilib- the biotites can be synthesized. Although 

rium or are dependent on growth factors, their properties and relations have not been 

The phlogopites from lavas are one-layer completely established, there is a complete 

monoclinic (iM) ; iM phlogopites are also series of solid solutions between phlogopite 

found, however, in metamorphosed lime- and eastonite. The members of the series 

stones. In the same hand specimen, two or are determined by the change in unit cell 

more of the polymorphs may be found, size. 

No clear relation between the temperature Experiments on reactions alleged to rep- 

of formation and the type of layering in resent the biotite isograd indicate that 

natural phlogopites has yet been deter- some muscovite-chlorite-quartz schists may 

mined. undergo the following reaction: musco- 

Phlogopite appears on the liquidus in vite + 2 clinochlore + 4 quartz <=^ phlog- 

the synthetic "haplogranite" under hydro- opite + 2 cordierite + 8 water. It can be 

thermal conditions. The formation of concluded that if this reaction takes place, 

phlogopite (and biotite) and the absence the growth of biotite in low-grade meta- 

of muscovite in lavas are accounted for by morphic rocks must be accompanied by 

their stability curves. another phase, such as cordierite. It has 

Phlogopite-museovite : Besides the im- been previously shown that the composi- 

portant problem of polymorphism in the tion of natural biotites does not lie on the 

micas, there is the question of the nature join connecting the compositions of natu- 

and extent of solid solution between the ral chlorites and natural muscovites. This 

various mica end members. Most signifi- strongly supports the view that biotite is 

cant of these is the common association of but one member of a reaction pair. It has 

a phlogopitic mica (i.e., a biotite) and mus- been observed that cordierite or andalusite 

covite. All field evidence points to limited accompanies the formation of biotite. On 

solid solution between muscovite and the assumption that the parent rock under- 

phlogopite, with one exception, the exist- going metamorphism is dominantly a 

ence of a mineral called mahadevite alleged muscovite-chlorite-quartz schist, the ap- 

to lie midway in composition between pearance of cordierite or andalusite may be 

muscovite and phlogopite. A recast of the regarded as an indication that the condi- 

four published analyses of mahadevite tions of the biotite isograd have been 

shows, however, that these minerals actu- reached. Whether biotite, cordierite, or 

ally lie on the join eastonite — muscovite andalusite is most conspicuous in the rock 

and are perhaps the purest eastonites would depend on the bulk composition of 

known. The experimental studies indicate the parent schist and probably also on 

that there is solid solution between musco- growth factors. It is interesting to note 

vite and phlogopite. The extent of the that the above reaction has been carried 

solid solution is being determined by out in the laboratory at temperatures as 

means of the changes in the unit cell di- low as 300° C. 

mensions as measured by X-ray diffraction. Seriate: The very fine-grained micas 

Biotite: The common mica biotite is common in the schists are loosely lumped 

complex in composition, but can be closely under the term sericite. Most such micas 

represented by the system phlogopite — are normal muscovite, but some have been 



68 



CARNEGIE INSTITUTION OF WASHINGTON 



identified as high-silica mica (phengite) 
and paragonite, the soda mica. For this 
reason the muscovite — leucophyllite, mus- 
covite — quartz, muscovite — paragonite, and 
muscovite — montmorillonite joins were in- 
vestigated. Both leucophyllite and mont- 
morillonite have more silica than musco- 
vite. In addition, it is conceivable that the 
fine-grained micas may contain small 
amounts of lithium, which would lead to 
a higher silica content if the structural 
scheme indicated for polylithionite ob- 
tained. 

Present data indicate that the primary 
mica formed from compositions on the 
muscovite — montmorillonite join is a hy- 
dromica as defined above. The phases 
formed from compositions on the quartz — 
muscovite join were quartz + hydromica 
+ sanidine. There was not sufficient evi- 
dence to determine whether or not solid 
solution was taking place according to the 
postulated structural scheme on the join 
muscovite — leucophyllite. Paragonite was 
synthesized, but no definite conclusions 
concerning the nature of the solid solu- 
tions with muscovite have yet been estab- 
lished. The synthesis of hydroxyl-bearing 
polylithionite was not accomplished. This 
failure may be due to the fact that most 
natural lepidolites contain considerable flu- 
orine instead of hydroxyl. Although it is 
not known whether or not fluorine is a re- 
quired constituent of the lepidolites, a poly- 
lithionite with some fluorine has been syn- 
thesized. 

In order to cast some light on the nature 
of the very fine-grained micas in sedi- 
ments, a new approach was employed. In 
the weathering and transport of rocks, the 
micas undergo severe treatment. One of 
the processes which reduce the mica is 
abrasion. A normal 2M muscovite was 
ground dry in an agate mortar for 30 
hours and samples were taken at 2-hour 
intervals. At the end of 6 hours of dry 



grinding, no crystal structure could be 
found from X-ray diffraction. At the end 
of 30 hours, no crystal structure could be 
found from electron diffraction, a tech- 
nique capable of 5 A resolution. The mica 
had apparently been reduced to or below 
its fundamental unit dimensions, approxi- 
mately 5X9X10 A. On recrystallization 
under hydrothermal conditions this mate- 
rial behaved in the same manner as other 
preparations, transforming in sequence 
from iMd to iM to 2M. It is possible that 
some sediments contain such unidentifi- 
able material which when metamorphosed 
produces mica. 

The mica polymorphs (Smith, Yoder). 
A theoretical study of the ways of stacking 
mica layers showed that there are only five 
simple ways of doing this which produce 
regular ordered structures: 1 -layer mono- 
clinic, 2-layer monoclinic, 3-layer trigonal, 
6-layer monoclinic, and 6-layer hexagonal. 
Disordered structures may be built which 
have randomly arranged slabs of layers. 
If only a very occasional stacking fault oc- 
curs, twinned crystals are produced. The 
possible twin laws were deduced from the 
theoretical study. A very simple way of 
describing the stacking was developed 
which consists simply in showing the posi- 
tions of the potassium atoms, thus reduc- 
ing the structure to its elementary simplic- 
ity and enabling an easy understanding of 
the various types of stacking. 

Six structures have been observed experi- 
mentally by Hendricks and Jefferson in 
their classic study of polymorphism in the 
micas. One of these, their 6-layer triclinic, 
has been shown by experimental work to 
be a differently described 2-layer mono- 
clinic form. Their 24-layer triclinic crys- 
tal has not been investigated further, but 
there is a suspicion that it also is 2-layer 
monoclinic. The other four structures are 
identical with the first four found theo- 



GEOPHYSICAL LABORATORY 



69 



retically. The remaining theoretical struc- 
ture, the 6-layer hexagonal, has not been 
found experimentally. The twinned crys- 
tals observed confirm one of the theoretical 
twin laws; the morphological studies de- 
scribed in the literature confirm another. 

The agreement between theory and ex- 
periment is therefore very good. Accurate 
measurements on the precession camera of 
i-layer monoclinic, 2-layer monoclinic, and 
3-layer trigonal crystals show that the 
assigned symmetry is exact and not merely 
pseudosymmetry. This conclusion answers 
various speculations presented in the liter- 
ature. 

The more important problem of dis- 



covering the factors which govern the 
growth of a particular polymorph in a 
certain set of geological conditions has not 
yet been solved. For example, muscovite 
prefers the 2-layer monoclinic structure, 
whereas phlogopite prefers the 1 -layer 
monoclinic or 3-layer trigonal structure. 
Unfortunately, no accurate structural anal- 
ysis exists, and we know only that the 
layers in muscovite are buckled whereas 
the layers in phlogopite are planar. The 
answer to the problem undoubtedly lies 
in accurately determining the atomic po- 
sitions in the polymorphs and then work- 
ing out the structural forces from those 
positions. 



OLIVINE AND ZEOLITE GROUPS 



Olivine (Yoder) . The study of the com- 
position of natural and synthetic olivine 
by X-ray methods has been greatly en- 
larged. Twelve synthetic and 23 analyzed 
natural olivines have been investigated, in 
addition to a host of natural olivines whose 
compositions were determined by optical 
methods. With the exception of two natu- 
ral specimens, the composition of olivine 
can be estimated to ±2 mole per cent by 
means of the X-ray method. The details 
of the technique and the determinative 
chart are being prepared for publication. 

High-pressure behavior of analcite (Yo- 
der, Weir). Compressions of analcite, a 
mineral found in rocks of the type believed 
to exist deep in the earth, indicate that a 
polymorphic transition takes place at ap- 
proximately 8400 atm (equivalent to 34 
km depth) and room temperature. The 



high-pressure transition was deduced from 
a small, but distinct, discontinuity in the 
volume decrements of analcites from 
Golden, Colorado, and Wassons Bluff, 
Nova Scotia. Two samples from the Tyrol, 
Austria, cut from some of the largest 
known single crystals, did not show a dis- 
continuity in the volume decrements, but 
gave an abnormal increase of compressi- 
bility with pressure. Such behavior usually 
precedes a transition, and it is predicted 
that the transition in the Austrian samples 
lies at pressures slightly higher than 10,000 
atm, the limit of the present experiments. 
There is no doubt, therefore, that a high- 
pressure modification of at least one rock- 
forming silicate does exist. This study 
was done in collaboration with Mr. Charles 
E. Weir, of the National Bureau of Stand- 
ards. 



CONTRIBUTIONS OF THERMOCHEMICAL AND X-RAY DATA 
TO THE PROBLEM OF MINERAL STABILITY 

T hermochemical properties of minerals calorimeter has been brought to a stage 

(Kracek, Neuvonen, Burley, Gordon), where it is possible to evaluate the heats 

During the past year the thermochemical of formation of many silicates, especially 

work with the hydrofluoric acid solution those containing alkali and aluminum 



7 o 



CARNEGIE INSTITUTION OF WASHINGTON 



atoms. The heats of formation are funda- 
mental physical constants which form the 
basis for theoretical deductions from ex- 
perimental thermochemical results. The 
determination of heats of formation of sili- 
cates containing alkali and aluminum has 
not been possible heretofore because reli- 
able heats of solution of the alkali oxides 
and of alumina as corundum were not 
available. The heats of solution of these 
oxides must be measured under the same 
experimental conditions that prevail in the 
determination of the heats of solution of 
the minerals concerned; the experimental 
difficulties which prevented earlier deter- 
mination are twofold: (a) the uncertain- 
ties involved in preparing and handling as 
well as dissolving reproducibly the alkali 
oxides in relatively strong acid at the tem- 
perature at which our calorimeter is oper- 
ated, and (b) the insolubility of corundum 
in the 20 per cent hydrofluoric acid em- 
ployed in the calorimeter. There are sev- 
eral types of aluminum oxide which are 
soluble in the acid, but these are in general 
somewhat indefinite products which would 
not serve as standard materials to be used 
in evaluating the heats of formation. The 
afore-mentioned difficulties were avoided 
by the methods to be briefly described. 

1. The alkali oxides: The heats of solu- 
tion of lithium, sodium, and potassium 
oxides in 20 per cent hydrofluoric acid at 
74.7 ° C were determined from two series 
of thermochemical measurements based on 
the heat of solution of the alkali chlorides 
and the heat of solution of the alkali sul- 
fates, together with the heats of other ap- 
propriate reactions. 

The chloride scheme of reactions in- 
volved: (1) heat of solution of the given 
alkali chloride, (2) heat of formation of 
the alkali chloride from the elements, (3) 
heat of formation of gaseous hydrogen 
chloride from the elements, (4) heat of 
solution of hydrogen chloride in water to 



form concentrated hydrochloric acid, (5) 
heat of solution of concentrated hydro- 
chloric acid in the calorimetric acid at 
74.7 , (6) heat of formation of liquid 
water, (7) heat of formation of the given 
alkali oxide, and (8) heat of solution of 
the proper quantity of water at 25° in the 
calorimetric solution at 74.7°. 

The sulfate scheme of reactions involved 
a parallel series of reactions, with the sub- 
stitution of alkali sulfate for alkali chlo- 
ride, and of sulfuric acid for hydrochloric 
acid. 

In both cases the heats of reactions (1), 
(5), and (8) were measured, and those of 
reactions (2), (3), (4), (6), and (7) were 
taken from the literature. The values ob- 
tained by the two schemes and their re- 
conciliation are presented in table 3. 

TABLE 3 

Heats of solution of alkali oxides in 20 per 
cent hydrofluoric acid at 74-7° c 



Oxide 


Reaction scheme 


Average* 


Differ- 


Chloride* 


Sulfate* 


CI - SO4 


Li 2 0... 
Na 2 0. . 
K 2 0. .. 


-59.36 

-87.66 

-109.61 


-60.86 

-89.19 

-110.37 


-60.11 

-88.42 

-109.99 


1.50 

1.53 
0.76 



* AH in kcal/mole oxide. 

2. Corundum: The heat of solution of 
corundum, the stable form of alumina, in 
20 per cent hydrofluoric acid at 74.7° C 
was determined from the following series 
of reactions: (1) heat of solution of pure 
aluminum, (2) heat of solution of an acid- 
soluble form of alumina, (3) heat of for- 
mation of liquid water, (4) energy to 
heat gaseous hydrogen from 25° to 74.7°, 
(5) heat of solution of liquid water at 25 ° 
in the calorimetric solution at 74.7°, (6) 
heat of formation of the particular acid- 
soluble alumina, obtained as the resultant 
of the heats of reactions (1) to (5), (7) 
heat of formation of corundum, (8) heat 



GEOPHYSICAL LABORATORY 



71 



of transition of the soluble alumina to 
corundum, obtained as the resultant of 
reactions (6) and (7), (9) heat of solution 
of corundum in the calorimetric solution, 
obtained as the resultant of reactions (2) 
and (8). 

Several acid-soluble aluminas were pre- 
pared for the purpose of measuring the 
heat of reaction (2). They were made 
from reagent-grade aluminum hydroxide 
powder by slowly raising the temperature 
to 350° C and holding at this temperature 
for about 24 hours. The composition of 
the resulting product was approximately 
A1 2 3 '0'5H 2 0. The temperature was 
then slowly raised to 600 ° and maintained 
for 3 or more days. This treatment re- 
sulted in a product containing in all cases 
less than 1 per cent water. The X-ray pat- 
tern agreed with that of gamma alumina, 
as defined by the Research Laboratory of 
the Aluminum Company of America. The 
particular product to which all the heats 
of formation will be referred was prepared 
from Baker's Analyzed C. P. Aluminum 
Hydroxide Powder, AI2O3 + *H 2 0, lot 
1 1 1428, for which x was found to be 3.019 
moles. The lot analysis indicated, "Sodium 
a trace." U. S. Geological Survey flame 
photometer analysis gave 0.42 per cent 
Na 2 and 0.04 per cent K2O. Correction 
was made for these on the assumption that 
they were combined in the preparation as 
alkali aluminate; the heat of solution of 
NaA10 2 was measured on a sample pre- 
pared by Schairer. In making the correc- 
tion, the small amount of potassium oxide 
was included with the sodium in the 
sodium aluminate. Other impurities were 
of negligible amount. 

The pure aluminum dissolved in reac- 
tion (1) was furnished by the Research 
Laboratory of the Aluminum Company of 
America. It contained as impurities: cop- 
per, 0.000; iron, 0.001; silicon, 0.002; mag- 
nesium, 0.001 per cent. Aluminum by dif- 



ference was 99.996 per cent. No correc- 
tion was applied for the small amounts of 
the impurities; a relatively large correction 
was necessary, however, for the heat lost 
by evaporation of water and hydrogen 
fluoride from the calorimetric solution by 
the evolved hydrogen. The aluminum was 
cut in strips, etched with hydrofluoric acid 
to remove surface iron, dried with alcohol 
and ether which were evaporated in an 
oven for a short time, and used as soon 
thereafter as possible. 

Numerical data: 1. Alkali oxides: The 
heat of solution of the alkali oxides may be 
expressed by the following type of reac- 
tion: Me 2 0(c, 25° C) + 2 H + (sol, t°) = 
2 Me + (sol, t°) + H 2 0(sol, t°) AH = x, 
where Me denotes Li, Na, or K; c, crystal- 
line; sol, 20 per cent hydrofluoric acid; t°, 
74.7 ° C; AH, heat of reaction per mole of 
oxide; x, numerical value of the heat of 
reaction AH. 

2. Corundum: The solution reaction in 
this case is: Al 2 3 (c, 25 ° C) + 6H + 
(sol, t°) = 2A1 +++ (sol, t°) + 3 H 2 
(sol, t°) AH = x, where the symbols have 
the same significance as above. In view 
of the importance of this reaction, a de- 
tailed summary of the heats of reaction in- 
volved in this determination is given in 
table 4. Among the heats of reaction in 
this table, those for reactions (1), (2), and 
(5) were measured, those for (3), (4), and 
(7) were taken from the literature, and 
the remaining ones, (6), (8), and (9), 
were computed from the others. We may 
call attention to the small heat of transi- 
tion for reaction (8), which is smaller 
than has been estimated by others, and 
smaller than its uncertainty. 

Heats of formation of silicates: Meas- 
urements were carried out of the heats of 
solution of a number of silicate minerals, 
some of which have already been pub- 
lished, and of several alkali silicates of in- 
terest for the work of this Laboratory and 



72 



CARNEGIE INSTITUTION OF WASHINGTON 



for petrological research in general. For 
computing the heats of formation, the 
needed heats of solution of the component 
oxides have been measured or evaluated as 
indicated above. The heats of formation 
are referred to the oxides, and in particular 

TABLE 4 

Heats of solution of corundum in 20 per cent 
hydrofluoric acid at 74-7° c 

Reaction AH (cal) 

(1) Heat of solution of 2A1 -287,590±420 

(2) Heat of solution of soluble 

alumina -92,136±410 

(3) Heat of formation of 3H 2 

at 25° C -204,951±30 

(4) Heat to raise 3H 2 from 25° 

to 74.7° C 1,036±20 

(5) Heat of solution of 3H 2 at 

25° in (sol, t°) 2,364±15 

(6) Heat of formation of soluble 

alumina from the elements 

at 25° -399,077±590 

(7) Heat of formation of corun- 

dum from the elements at 

25° -399,090±240 

(8) Heat of transition of soluble 

alumina to corundum at 

25° -13±640 

(9) Heat of solution of corun- 

dum at 25° in (sol, t°) . . . -92,123±760 



to silica as quartz, and alumina as corun- 
dum. The heats of solution are corrected 
so that the resultants of the thermochem- 
ical summations are heats of formation at 
25 ° C = 298.1 6° K. This may be repre- 
sented technically by the process : materials 
at 25° C dissolved at t° = 74-7° C. The 
alkali silicates were prepared in the ther- 
mochemical laboratory; the other silicates 
are natural or synthetic materials, for most 
of which the heats of solution have already 
been published. The values are given in 
tables 5 to 8. Table 5 gives the heats of 
solution of the oxides; table 6, the heats 
of solution and formation of the alkali 
silicates, together with the heats of phase 
change at 25° C; table 7, the differences in 
the heats of solution for homologous series 
of silicates of a given alkali metal in com- 
parison with the heats of solution of the 
various forms of silica; and finally, table 8, 
the heats of formation for the minerals 
studied. 

Significance of the silicon-oxygen and 
aluminum-oxygen distances in paracelsian 
and high-came gieite (Smith). Several 
minerals (including the feldspars) have 
both aluminum and silicon in tetrahedral 
co-ordination. The structural changes in 



TABLE 5 
Heats of solution of certain oxides, dissolved from 25 C in 20 per cent 

HYDROFLUORIC ACID AT 74-7° C 



Oxide How measured 

Li 2 Indirectly, average value 

Na 2 Indirectly, average value 

K 2 Indirectly, average value 

MgO Directly, by Sahama and Torgeson 

CaO Directly 

AUO3 (soluble) Indirectly 

A1 2 3 (corundum) Indirectly 

Si0 2 (quartz) Directly 

Si0 2 (cristobalite) Directly 

Si0 2 (glass) Directly 

Ga 2 3 (beta)* Directly 

* Supplied by J. R. Goldsmith, University of Chicago. 



tf(kcal/mole) 



-60.11 


±0.75 


-88.42 


±0.76 


-109.99 


±0.38 


-38.75 




-55.72 


±0.07 


-92.136±0.410 


-92.123±0.760 


-33.30 


±0.04 


-33.93 


±0.03 


-35.48 


±0.02 


-51.61 


±0.75 



GEOPHYSICAL LABORATORY 



73 



TABLE 6 
Thermochemical properties of certain lithium, sodium, and potassium silicates 



Substance and condition 



AH (sol, 74.7° C) 
(kcal/mole) 



Latent heats of phase 
change at 25° C, x ->- gl 



(kcal/mole) 



(cal/g) 



AH f at 25° C 
from oxides 
(kcal/mole) 



Li 2 Si0 3 (crystalline) -58.96 

Li 2 Si 2 5 (glass) - 103 . 56 

Li 2 Si 2 0s (crystalline) — 92 . 13 

Na 2 Si03 (crystalline) — 65 . 66 

Na 2 Si 2 5 (glass) -104.70 

Na 2 Si 2 5 (E) - 101 . 98 

Na 2 Si 2 5 (A) -100.04 

Na 2 Si 2 5 (B) -99.45 

K 2 Si 2 5 (glass) - 103 . 54 

K 2 Si 2 5 (crystalline) -99.07 

K 2 Si 4 9 (glass) -173.87 

K 2 Si 4 9 (crystalline) - 169 . 25 

x, crystalline; gl, glass; E, A, B, polymorphous forms. 



11.42 

2.72 
4.66 
5.25 

4.47 
4.62 



76.2 

14.9 

25.5 
28.8 

20.9 
13.8 



-34.45 
-23.15 
-34.58 
-56.06 
-50.32 
-53.04 
-54.98 
-55.57 
-73.05 
-77.52 
-69.32 
-73.94 



TABLE 7 

Differences for i Si0 2 increment in the heats of solution of alkali silicates 

(in kilocalories per mole) 

Silicate Difference in heat of solution 

Lithium (disilicate-metasilicate) —92.13+58.96 = —33.17 

Sodium (disilicate E-metasilicate) —101.98+65.66 = —36.32 

Sodium (disilicate A-metasilicate) —100.04+65.66 = —34.38 

Sodium (disilicate B-metasilicate) —99.45+65.66 = —33.79 

Potassium (tetrasilicate-disilicate) ^(-169.25+99.07) = -35.09 

For comparison : 

Si0 2 (quartz) -33 . 30 

Si0 2 (cristobalite) -33 . 93 

Si0 2 (glass) -35 .48 



the feldspars, such as the change caused by 
sanidinization of orthoclase, are almost 
certainly caused by order-disorder of the 
silicon and aluminum atoms. Since the 
electron densities of silicon and aluminum 
are too close for distinction by X-rays, we 
have to rely on measurements of Si-O and 
Al-O distances, and it is very important 
that these be known accurately. Although 
good values have been obtained for Si-O, 
giving Si-O = i.6o±o.oi A, no suffi- 
ciently accurate measurements have pre- 



viously been made for Al-O. In paracel- 
sian, Sii/ 2 Ali/ 2 -0 is 1.696 ±0.01 A; and in 
carnegieite Si-O = 1.587 ±0.02 A, and 
Al-O = 1.767 ±0.02 A. The reliable values 
of (Si, Al-O) are plotted against percent- 
age of Al in figure 12. It will be seen that 
the measured values are consistent with a 
linear variation between Si-O = 1.60 ± 
0.01 A and Al-O = 1.77 ±0.02 A. The 
result was encouraging, for it was previ- 
ously thought from a consideration of the 
older, less accurate values that Si-O = 1.62 



74 



CARNEGIE INSTITUTION OF WASHINGTON 



TABLE 8 
Thermochemical properties of certain silicate minerals 



AH/ at 25° C 
from oxides 
(kcal/mole) 



AH 

Mineral (sol, 74.7° C) 

(kcal/mole) 

Albite, natural, Amelia, Virginia — 149 . 79 

Albite, natural, Varutrask, Sweden — 148 . 12 

CaAl 2 Si 2 08, anorthite, synthetic — 185 . 11 

CaAlGaSi 2 8 , Ga anorthite, synthetic* — 170 . 80 

Orthoclasef — 144 . 54 

Nepheline, synthetic — 87 . 33 

Jadeite, Burma — 1 14 . 96 

Jadeite, Japan — 115 . 14 

Leucite, Vesuvius — 1 16 . 08 

Diopside, synthetic —123.31 

Wollastonite, synthetic —65.36 

Pseudo-wollastonite, synthetic —66.92 

* Supplied in the form of glass by J. R. Goldsmith, University of Chicago. 

t Value derived from heats of solution of iron-bearing orthoclases from Madagascar. 



-40.38 
-42.05 
-29.33 
-23.38 
-56.41 
-36.24 
-41.91 
-41.73 
-51.57 
-37.76 
-23.66 
-22.10 



and Al-O = 1.72, a difference only half 
as great as that now found. By careful 
work, using two-dimensional analyses, it 
should be possible to determine the order- 
ing of the aluminum and silicon atoms. 




Si-0 AI-0 

Fig. 12. Variation of the (Si, Al-O) distance 
in oxygen tetrahedra from Si-O to Al-O. The 
values for Si-O are for high- and low-quartz, 
high- and low-cristobalite, diopside, afwillite, 
tilleyite, and high-carnegieite. 



Previously it was thought that only the 
very laborious three-dimensional analyses 
could do this. (It should be noted that 
these values are the mean of the four tet- 
rahedral distances in the oxygen tetra- 
hedron.) 

A careful review of the most accurately 
measured Si-O distances shows that there 
is no evidence that the mean Si-O distance 
in any one tetrahedron is affected either by 
the method of linkage of the tetrahedra to 
form chains, sheets, frameworks, etc., or 
by the presence of neighboring cations (ex- 
cept possibly by very extreme distribution) . 
There is, however, evidence that individual 
Si-O distances vary in such a way that an 
oxygen atom linked to two silicon atoms 
is 0.05 A more distant from the silicon 
atoms than an oxygen atom linked to only 
one silicon atom. 

These results show that to a high degree 
of approximation the silicon tetrahedron 
contributes about the same amount of lat- 
tice energy to each of the various minerals 
which contain it, for lattice energy is a 
function of interatomic distance. 

The crystal structure of paracelsian 



GEOPHYSICAL LABORATORY 



75 



(Smith). A preliminary report of this de- 
termination was given in the last annual 
report. The structure analysis was com- 
pleted by the aid of a new modification of 
the Fourier series, which showed very 
clearly the reason for the pseudosymmetry 
of paracelsian. It is caused by very small 
movements of related atoms which destroy 
the orthorhombic symmetry to produce the 
lower monoclinic symmetry. These move- 
ments are almost certainly produced by 
segregation of aluminum and silicon 
atoms. It appears likely that when first 
formed, paracelsian has true orthorhombic 
symmetry, resulting from complete dis- 
order of the aluminum and silicon atoms. 
On cooling, the thermal motion which pro- 
duces the disorder is lessened, and the 
aluminum and silicon atoms then segre- 
gate into their preferred positions, thus 
giving monoclinic symmetry. This be- 
havior is the same as that thought to exist 
in the feldspar series. 

Comparison of the feldspar structure 
with the paracelsian structure shows much 
similarity. The two structures are built up 
of almost identical spirals, the difference 
being in their cross-linkage. As this should 
provide only a small energy difference, it 
undoubtedly is the reason why celsian (a 
feldspar) and paracelsian occur together. 

Some useful data on the interatomic 
distances for barium atoms were obtained 
and compared with those in barium titan- 
ate, a ferroelectric material with intriguing 
commercial possibilities. 

The crystal structure of high -came gieite 



(Smith). High-carnegieite is the stable 
form of NaAlSi0 4 above 1248° C. Below 
this temperature nepheline is the stable 
form, but high-carnegieite exists below 
1248 ° C as a metastable form, and at 
690° C there is a high-low inversion to 
low-carnegieite. The new determinations 
give a more complete explanation of the 
X-ray data than did the work in the Lab- 
oratory by Barth in 1932. The structure 
has the same framework of tetrahedra as 
cristobalite except that half the silicon 
atoms are replaced by aluminum. To bal- 
ance the charge, an equal number of so- 
dium atoms occupy holes in the cristobalite 
framework. Like cristobalite, carnegieite 
has a statistically random arrangement of 
oxygen atoms such that they appear to 
rotate in a circle of 0.5 A radius. Whether 
this is a true relation or only a space and 
time average cannot be determined. This 
rotation is surely a remarkable phenome- 
non in a rigid crystal which has an exact 
repeat distance for hundreds of unit cells. 
X-ray crystallographers think that many 
silicates are disordered at high tempera- 
tures, though not always so badly as this. 
It is desirable that much work be done on 
these high-temperature crystals in order to 
elucidate the principles which govern their 
structures. All minerals of igneous origin 
are formed at high temperatures, and for 
an understanding of their growth a study 
of high-temperature structures is pertinent. 
The high-low inversion of carnegieite is 
caused by either (a) collapse of the high 
structure around the holes, or (b) cessa- 
tion of rotation, or both. 



APPLICATION OF TRACE ELEMENTS 



Trace elements in some metamorphic 
rocks (Eugster). The optical spectrograph 
has been a very useful tool in the study 
of cosmic and terrestrial abundances of 
trace elements. In the past decades a large 



fund of information has been accumulated 
on average concentrations and modes of 
occurrence of most elements; but few at- 
tempts have been made to apply this 
knowledge to specific geological problems. 



7 6 



CARNEGIE INSTITUTION OF WASHINGTON 



The distribution pattern of certain key nite signs of chemical precipitation, as well 

elements will depend largely on the course as biological influence. 

of the fractionation processes acting dur- Some of the results of the investigation 

ing the formation of the rocks. There is can be summarized as follows: 

little doubt that the statistical treatment Alkali metals. For the alkali metals the 

of the behavior of trace elements in a par- best correlation was found in the pair po- 

ticular geological environment represents tassium-rubidium, as was to be expected. 

a powerful tool for a variety of problems. For all inorganic rocks the ratio potas- 

In order to test this viewpoint, a suite of sium/rubidium assumes a nearly constant 

33 metamorphosed sediments was studied value of about ioo. The potassium/rubid- 

with an optical spectrograph. The sped- ium ratio is also constant for all rocks with 

mens are from an Alpine area (Aarmas- organic influence such as coal ashes, gra- 

siv) on which detailed petrological studies phitic phyllites, and graphite quartzites, 

had been made earlier. Such detailed geo- but with a definite enrichment of rubidium 

logic information is a prerequisite to intel- over potassium (potassium/rubidium about 

ligent sampling. Duplicate measurements 65). The concentrations vary for coal 

for 18 elements were carried out at the ashes from 10 to 100 ppm Rb 2 0, and for 

Cabot Spectrographic Laboratory of the the other rocks from about 100 to 1800 ppm 

Department of Geology and Geophysics, Rb 2 0. 

Massachusetts Institute of Technology, Cesium values lie very close to the de- 
Cambridge, Massachusetts. The elements tection limit. Cesium seems to behave very 
included lithium, sodium, potassium, ru- much like rubidium, although in coal 
bidium, cesium, copper, gallium, lead, sil- ashes there is a slight enrichment of cesium 
ver, thallium, titanium, zirconium, nickel, over rubidium. 

vanadium, scandium, chromium, stron- Sodium increases in coal ashes with in- 

tium, and boron. All trace elements pres- creasing total alkali content, but definitely 

ent in amounts above the normal detection decreases in rocks without organic influ- 

limit were determined for each sample ence, with increasing potassium content, so 

without resort to chemical concentration, that for these rocks the sum Na 2 + K 2 

The rocks involved in this investigation stays nearly constant, 

are probably of Carboniferous age (Ste- Lithium is clearly enriched in hornfelses 

phanian) and were deposited in a small in- near the granite contacts, probably by 

tracontinental lake during the Hercynian pneumatolytic processes, but otherwise fol- 

orogenesis. They suffered an over-all re- lows sodium rather closely, 

gional and dynamic metamorphism during The concentration of the alkali metals 

the Alpine orogenesis, including strong is probably to a great extent governed by 

shearing forces and differential move- differential absorption from true solutions 

ments. Furthermore, some hornfelses are by clay particles, although detrital influ- 

to be found at the contacts of granites and ences, especially from plant residues, can- 

monzonite-batholiths. The main rock not be excluded. 

types are now phyllites (chlorite-sericite), Chromium, nickel, scandium, titanium, 
biotite-amphibole schists, hornfelses (sil- zirconium, gallium. Addition of very flne- 
limanite, chiastolite, or cordierite-garnet) , grained heavy minerals is probably re- 
graphitic quartzites, and small coal lenses, sponsible for the presence of these ele- 
The sedimentation was to a large extent ments. 
mechanical (detrital) but also shows defi- Chromium and nickel show in all in- 



GEOPHYSICAL LABORATORY 



77 



organic rocks a very good correlation over 
a wide range of concentration (5-1000 
ppm). Both are probably located in the 
same sulfides or silicates; in the silicates, 
mainly in augite and amphibole, in which 
Cr +3 substituted for Fe +3 , Ni +2 for Mg +2 . 
This correlation holds even for most coal 
ashes, but with a markedly greater scatter. 

Scandium: The correlation between 
scandium and nickel or chromium is poor 
for all inorganic rocks and very poor for 
the coal ashes. This means that most of 
the chromium and nickel must be con- 
tained in sulfides, because Sc" h3 is typically 
lithophile and substitutes for Mg +2 and 
Fe +2 in the same silicates as do chromium 
and nickel, as part of the complex substitu- 
tion Sc +3 A1 +3 <=± Mg +2 Si +4 . This must be 
particularly true for the coal ashes. 

Titanium shows a behavior rather simi- 
lar to that of scandium, especially in the 
inorganic rocks. Therefore, it can be sus- 
pected that most of the titanium occurs in 
the same complex silicates as scandium, 
and that only a small or constant amount 
of special titanium minerals such as rutile 
and sphene is present. This does not hold 
to the same extent for coal ashes, where a 
greater part of the titanium seems to be 
contained in rutile or sphene. 

Zirconium increases in coal ashes paral- 
lel to scandium and titanium, but charac- 
teristically decreases in the same rocks with 
increasing chromium and nickel content. 
In all the inorganic rocks zirconium shows 
a very uniform distribution, with values 
between about 140 and 200 ppm. This uni- 
formity is probably due to the presence of 
a constant amount of zircon. 

Gallium, mainly replacing Al +3 , reveals 
in these rocks the same trends as in most 
other rock types, a very uniform concen- 
tration of about 12-30 ppm. Only in a few 
coal ashes do the values drop to 3-5 ppm. 

Vanadium, copper, boron, strontium. 



Vanadium, as would be expected, dis- 
closes excellent correlation with scandium 
and titanium, as far as the inorganic rocks 
are concerned, the vanadium concentration 
varying from 100 to 350 ppm. V +4 substi- 
tutes for Ti +4 ; V +4 and V +5 substitute for 
Al +3 and Fe +3 in the complex silicates. On 
the other hand, in most of the coal ashes 
a strong enrichment of vanadium can be 
found, with values up to 1600 ppm, which 
is typical for biological environment. But 
some of the coal beds from a slightly dif- 
ferent region gave exceptionally low val- 
ues (30-50 ppm). Because several coal 
beds are of allochthone origin, these low 
values may be related to washing out of 
the vanadium from the plant residues. 

Copper occurs in a completely erratic 
way, and no correlation with any of the 
other elements (especially chromium and 
nickel) could be found. Nevertheless, 
most of the coal ashes show a definite en- 
richment in copper (25-160 ppm) as com- 
pared with the other rocks (6-50 ppm). 

Boron concentrations were found to vary 
between the limits of 3 and 180 ppm and 
to be independent of the distribution of 
any other element. High boron contents 
are typical for all hornfelses (pneumato- 
lytic processes), as well as for some of the 
residual schists (detrital tourmaline). The 
values for coal ashes are scattered over the 
whole range, with biological enrichment 
only in certain coal beds. 

Strontium values are rather low (30- 
200 ppm) in most of the phyllites, espe- 
cially in aluminum- and potassium-rich 
sericite phyllites, and are significantly 
higher (250-980 ppm) in all biotite-amphi- 
bole schists. Sr +2 substitutes for Ca +2 . Bio- 
logical enrichment must be suspected in 
some of the coal ashes (100-270 ppm), 
whereas others are extremely poor in 
strontium (5-10 ppm). 

The remaining elements (lead, silver, 



7 8 



CARNEGIE INSTITUTION OF WASHINGTON 



thallium) could be detected only in certain 
specimens, and they occur in too small 
amounts to permit any conclusions. 

For the inorganic rocks no significant 
differences could be found between the 
different rock types, for instance phyllites, 
schists, hornfelses. Therefore, if migration 
took place during the recrystallization, it 



was of insignificant magnitude. An excep- 
tion is the enrichment of lithium and bo- 
ron in hornfelses near the granite contacts. 
These few data show that the main 
trends of sedimentation for this particular 
environment, mechanical, chemical, and 
biological, are clearly reflected in the distri- 
bution of the trace elements. 



AGE OF ROCKS 



In 1952, a co-operative program was be- 
gun by the Department of Terrestrial Mag- 
netism and the Geophysical Laboratory to 
determine the age of rocks by use of special 
methods on the various minerals in the 
rock, and to make a critical comparison 
of the reliability of these methods. This 
program has been actively followed during 
the past year. At the present time, how- 
ever, such a critical comparison has not 
been completed. Therefore the ages given 
are simply the numerical results of the 
analyses, using the now accepted half lives 
and decay schemes of the elements in- 
volved. Any future changes in these may 
materially affect the final values. 

Isotope dating of igneous intrusives 
(Aldrich, Davis, Graham, Nicolaysen, Til- 
ton) . There are many reasons for develop- 
ing techniques to fix accurately the age of 
rocks, but one of the most immediate is 
the demand for raw materials which forces 
the practical geologist to find new source 
areas. The search for such areas is usually 
based on the assumption that ore bodies 
tend to accumulate in similar geological 
environments and at similar geological 
times of mineralizing activity. It is pos- 
sible for the geologist to locate those sim- 
ilar places which could be areas for ore 
deposition, but he is not always able to 
determine whether or not the constituent 
rocks were formed at a time when ore 
deposition is known to have taken place. 



Accurate age determinations will greatly 
facilitate such a search. 

There are many methods for determin- 
ing the age of a rock, some absolute, others 
relative. Until recently, methods of abso- 
lute age determination have been limited 
in application to ores of radioactive ele- 
ments (e.g., uranium and thorium) for 
which chemical determination of the par- 
ent and daughter elements is possible. For 
wider use, it was necessary to develop tech- 
niques for the accurate measurement of 
these elements in common rocks, where the 
concentration may be only several parts 
per million. The method of isotopic dilu- 
tion proved satisfactory and permitted ex- 
tension of the technique to other radio- 
active elements such as potassium and ru- 
bidium ("Determination of thorium by 
isotope dilution"). The increased sensitiv- 
ity of the isotopic dilution method makes 
possible for the first time age determina- 
tions by several radioactive decay systems 
on a single rock, thus providing an oppor- 
tunity to compare the reliability of the 
various decay systems for dating the rock. 
When the most reliable methods are as- 
certained, a large variety of geochemical 
and geophysical problems can be studied. 
In addition, the availability of source-dated 
minerals permits a study of natural nuclear 
physical rate processes such as branching 
ratios, neutron flux in rocks, and natural 
fission. 

The program, which has been executed 



GEOPHYSICAL LABORATORY 



79 



in part, consists first in collecting large 
quantities of a few common rocks from 
which the constituent minerals suitable for 
age determination may be easily isolated 
("Preparation of specimens"). The min- 
erals which have been separated include 
zircon, sphene, apatite, biotite, lepidolite, 
and perthite. A known weight of each 
mineral, to which have been added known 
amounts of stable isotopes, is then decom- 
posed by appropriate reagents. When the 
desired elements have been separated from 
the resulting homogeneous solution by spe- 
cial processes, they are analyzed by mass 
spectrometer, and each element's absolute 
concentration in the mineral is thereby de- 
termined. The program includes the de- 
termination of U 238 , Pb 206 , Pb 207 , Pb 208 , 
Th 232 , Rb 87 , Sr 87 , K 40 , Ca 40 , and A 40 for 
each mineral. The ages based on the emis- 
sion of alpha particles are given by the 
ratios Pb 207 /Pb 206 ("Lead-lead ages"), 
Th 232 /Pb 208 ("Thorium-lead ages"), and 
U 238 /Pb 206 ("Uranium-lead ages"). Those 
ages based on beta particle emissions are 
given by the ratios Rb 87 /Sr 87 ("Rubidium- 
strontium ages"), K 40 /Ca 40 , and K 40 /A 40 . 
Considerable progress has been made in 
the age-determination program in spite of 
the many technical difficulties. The ages 
based on alpha emissions have been ob- 
tained for several minerals in three gran- 
ites. As yet the ages for the same minerals 
based on beta emissions have not been done, 
but the techniques are now being worked 
out on more satisfactory material for which 
the age is also of considerable interest. The 
results obtained cast some doubt on the 
assumption that the age of a rock can be 
determined solely from a single mineral 
("Transfer of lead in the Essonville gran- 
ite"). In addition, the ambiguity of the re- 
sults from the various lead age techniques 
points up the necessity for further work 
on the source of errors, but final analysis 



of the many problems encountered must 
await the results of the entire program. 

Determination of thorium by isotope di- 
lution. The technique which has made the 
present age studies possible is described in 
detail for the element thorium. The stable 
isotopes necessary for the practical execu- 
tion of the technique have been made avail- 
able by the Atomic Energy Commission. 

Thorium in thorium-bearing minerals 
has but one isotope, as shown in figure 
13a. In order to determine thorium by 
the method of isotope dilution, another 
isotope of thorium in milligram quanti- 
ties is needed. Th 230 is a daughter of U 238 , 
of sufficiently long half life to be present in 
nearly pure form in originally thorium-free 
uranium minerals. Since Th 230 is not yet 
available from the AEC, about 1 mg of 
such thorium was extracted from an old 
pitchblende and made into the carrier solu- 
tion. The isotopic composition of the car- 
rier material is shown in figure 13^; the 
ratio Th 230 /Th 232 is about 4. The carrier 
solution is calibrated from this ratio and 
from the ratio of a mixture of a known 
volume of the carrier solution to a known 
mass of Th 232 . The isotope distribution of 
the mixture is shown in figure i3<r. The 
thorium in a rock is determined by equi- 
librating a known volume of carrier solu- 
tion with a solution containing all the 
thorium of the specimen. A fraction of 
the thorium sufficient for mass spectro- 
metric analysis is then extracted and ana- 
lyzed, and the isotope distribution so ob- 
tained (fig. i^d) is used to calculate the 
thorium content of the rock or mineral. 
The method is applicable to all elements 
which have two stable or long-lived iso- 
topes, and is only slightly more complex 
when the element to be analyzed has 
several isotopes. 

Preparation of specimens. An extensive 
field trip to the mapped Pre-Cambrian 



8o 



CARNEGIE INSTITUTION OF WASHINGTON 



areas of southern, southwestern, and west- 
ern United States was made by a party of 
Institution geologists, chemists, and physi- 
cists to collect granites and pegmatitic min- 
erals for laboratory investigation. Granites 
were collected from sixteen significant lo- 
calities, and lepidolites were obtained from 



and their support and assistance proved to 
be invaluable in obtaining representative 
materials. 

Thin sections of all rock samples were 
prepared for petrographic examination, 
and the granites were crushed for mineral 
separation. Combinations of magnetic and 



6 r 



< 

M 
ID 

< 

Z 
- 3 

I- 
Z 
u 
(T 

<r 

Z 

o 

tr 

S3 i 

Ul 

_! 



230 232 
NORMAL THORIUM 




230 



232 



Th 230 CARRIER 



230 232 

0.100 ml CARRIER 
SOLUTION 

+ 

0.0946 9 CAPE ZIRCON 

Fig. 13. Mass spectra for determination of thorium by the method of isotope dilution 



232 
3.496/ NORMAL Th 

+ 
0.100 ml CARRIER 
SOLUTION 



five pegmatites, four of which were seem- 
ingly associated with granite bodies. Ac- 
companying minerals such as feldspar, bio- 
tite, muscovite, amblygonite, beryl, and 
tourmaline were also collected at the peg- 
matite localities for laboratory evaluation 
as to their suitability either for age de- 
termination or for measurement of isotope 
ratios. Wherever possible, geologists work- 
ing in the particular areas were consulted, 



density separations were employed to yield 
pure samples of the constituent minerals. 
In some unfavorable cases 50 pounds of 
rock yielded but 100 mg of zircon, barely 
enough for preliminary analysis. Mineral 
fractions of zircon, sphene, and biotite 
were extracted from a granite collected at 
Cape Town, Union of South Africa, and 
from a heavy mineral concentrate from a 
granite in Southern Rhodesia, obtained 



GEOPHYSICAL LABORATORY gl 

through the co-operation of Dr. A. M. nearly intact owing to its younger age and 
MacGregor, of the Rhodesian Geological lower radioelement concentration. Since 
Survey. zircon is one of the most stable minerals 

Lead-lead ages. The lead analyses are known, the Cape zircon therefore repre- 
the collaborative work of Dr. Claire C. sents one of the most favorable subjects for 
Patterson, of the California Institute of thorium-lead age measurement on a rock 
Technology. The leads of three granites mineral. It is seen that the thorium-lead 
have been studied during the past year: and uranium-lead ages agree much more 
Essonville, Ontario; Uncompahgre, Colo- closely for the Cape than for the Essonville 
rado; and Cape Town, Union of South zircon. Allowing for the fact that the 
Africa. The ages obtained from these Cape lead data are still of a preliminary 
measurements are given in column 2 of nature, this agreement indicates that tho- 
table 9. The values have an analytical ac- 
curacy of about 5 per cent, unless other- 
wise indicated. The Cape zircon ages are 
based on preliminary data and are accurate 
to about ±10 per cent. 

Thorium-lead ages. The striking fea- 
ture of the thorium-lead ages is the fact 
that they are all much lower than the 
uranium-lead and lead-lead ages of the 
same minerals (table 9) . This discrepancy 
has been found by other workers for a 
number of the uranium-thorium ores. In 
particular, five of the six monazite age de- 
terminations reported in the literature re- 
semble the data of table 9 in having low 
thorium-lead ages as compared with the 

uranium-lead ages, but no adequate expla- rium age discrepancies in zircons may be 
nation has been offered for these observa- a function of the interrelated quantities, 
tions. Since it now appears that many the radioelement concentration, and the 
granitic minerals can be expected to yield extent of crystal damage, 
low thorium-lead ages, it is probable that Another interesting result which may 
the goal of future thorium work will be contribute to our understanding of this 
more to determine the cause of the dis- problem has been obtained by leaching the 
crepancy than to measure ages by this Essonville sphene with cold 6N hydro- 
method. Some progress has been made chloric acid and analyzing the solution, 
with the problem during the past year, al- The solution was found to contain 20 per 
though the data are too few to permit cent of the sample's uranium, 40 per cent 
generalization. of its thorium, and 70 per cent of its lead. 

The comparison between the Essonville Moreover, the acid removed 65 per cent 
and Cape zircons, however, is illuminat- of the radiogenic Pb 208 , but only 25 per 
ing. X-ray examinations showed that the cent of the radiogenic Pb 206 . Thus for this 
crystal structure of the Essonville zircon is mineral the lead generated by thorium is 
badly shattered by radiation damage (met- more susceptible to removal than that gen- 
amict), whereas that of the Cape zircon is erated by uranium. These observations 





TABLE 9 




Lead 


AGES OF 


GRANITIC MINERALS 








Age (million years) 




Sample 
















U 238 /Pb ; 


206 Pb2"VPb 206 Th 


232 /Pb 208 


Essonville 








granite: 








Zircon .... 


1030 


1060 


415 


Sphene. . . . 


920=b80 1060±200 


202 


Uncompahgre 








granite: 








Apatite. . . . 


1050 


1810±160 


200 


Biotite 


3200 


1700 


1200 


Cape granite: 








Zircon .... 


347 


550 


278 



82 



CARNEGIE INSTITUTION OF WASHINGTON 



might indicate that loss of Pb 208 rather 
than addition of thorium is the cause of 
the low thorium-lead age for the mineral. 
It is possible to lose Pb 208 without a pro- 
portionate loss of Pb 206 , if there is an in- 
homogeneous distribution of uranium and 
thorium in the crystals. 

In the case of the Essonville zircon it has 
been found that a hot aqua regia leach will 
reduce the alpha activity of the mineral by 
35 per cent. This leach solution will be 
studied in the same manner as the sphene 
leach solution, in an effort to obtain further 
information on the problem of low tho- 
rium-lead ages. 

Uranium-lead ages. The uranium-lead 
age of the Cape zircon (table 9) is less 
than the lead-lead age by an amount that 
is far outside the limits of analytical er- 
ror. It is believed that the lead-lead age is 
the more nearly correct and that the ura- 
nium-lead age is low. The Essonville 
zircon occurred in the rock as large crys- 
tals several millimeters in diameter, 
whereas Cape zircon occurred as small 
crystals but a few hundreths to a tenth of 
a millimeter in diameter. The hypothesis 
now favored is that the smaller size of 
the Cape zircon crystals permitted lead 
loss while the larger size of the Esson- 
ville crystals prevented it. We have no 
data for the diffusion rate of lead in zir- 
con, but data exist for the diffusion of 
lead in a perthite feldspar which indicate 
that it could diffuse in the mineral over 
distances of approximately 0.1 mm in one 
billion years at 300° C under the influence 
of a concentration gradient. 

Rubidium-strontium ages. The rubid- 
ium-strontium measurements have been 
extended to include some 25 lithium micas, 
obtained from pegmatites located in Pre- 
Cambrian areas of South Africa and North 
America. Table 10 gives the measurements 
on South African lepidolites, and table 11 



those for North America. The absolute 
ages are determined from a decay con- 
stant for Rb 87 of 1.13X io -11 yr _1 , the aver- 
age of two recent determinations by ab- 
solute beta counting. There is a possibility 
that this decay constant may be revised in 
the future if the existence of an unusual 

TABLE 10 

Apparent ages of South African 
lepidolites 

Age 
Pegmatite location (million 

years) 

Popes Claim, S. Rhodesia 374° 

Letaba, Transvaal 3850 

Hombolo, Tanganyika 3 2 5° 

M'bale (1), Uganda 2460 

M'bale (2), Uganda 2370 

Lunya, Uganda 2 34° 

Kinderzitt, Namaqualand 1210 

Jakkalswater, Namaqualand 1100 

Muika (1), Belgian Congo 1220 

Muika (2), Belgian Congo 1210 

Karibib-Usakos II, SW. Africa 600 

Sahatany, Madagascar 690 

Alto Ligonha, Mozambique 570 

Dogon Daji, Nigeria 625 

TABLE 11 

Apparent ages of North American 
lepidolites 

Age 
Pegmatite location (million 

years) 

Bagdad, Arizona 2660 ±260 

Bonneville, Wyoming 3570 ± 300 

Dixon, New Mexico 3450 ±400 

Ohio City, Colorado 3440 ± 300 

type of radioactivity — "bound beta decay" 
— can be proved. Diffusion of rubidium or 
radiogenic strontium out of the crystal lat- 
tice would also lead to erroneous ages. Loss 
of rubidium would increase the measured 
age. 

The values presented in table 10 are simi- 
lar to some of those published in last year's 



GEOPHYSICAL LABORATORY 



83 



report. The ages of specimens collected 
from different pegmatites in a geologically 
homogeneous area agree within 10 per cent. 
In one instance, however, the disagreement 
between these measurements and published 
syntheses of African Pre-Cambrian tecton- 
ics is so striking that the need for caution 
in interpreting rubidium-strontium ages is 
again highlighted. 

The results in table 11 suggest the exist- 
ence of a Pre-Cambrian area in the United 
States as ancient as any in North America. 
Geographically, the three pegmatites with 
ages of about 3500 million years are located 
roughly between the 2000-million-year-old 
pegmatites of the Black Hills, reported last 
year, and the 2700-million-year-old pegma- 
tite at Bagdad, Arizona. If other dating 
methods support these interpretations, the 
work will have important bearing on theo- 
ries of continent formation. The existence 
of very ancient minerals in the United 
States as far south as New Mexico is impor- 
tant to theories of continent formation. 
These measurements are also a part of the 
study of the correlation of ages determined 
by different radioactive decay systems. 

An attempt was made this year to see 
whether the large variation in the isotopic 
abundances of the isotopes of strontium 
thought to be stable could be due to radio- 
active decay of zirconium or uranium 
contained in the mineral zircon. The ab- 
solute amount of strontium in the blank 
run in parallel with the zircon was 2.5 ± 
0.5 micrograms. That found in one gram 
of zircon was within 20 per cent of this 
amount. This can be considered good 
agreement between two blank runs. It is 
therefore concluded that the radioactive 
decay of zirconium or uranium in the 
amounts present in the mineral biotite 
could not contribute in any way to the 
variation of the ratio Sr 86 /Sr 88 found in 
biotite. It is of interest to note that the 
strontium determination in zircon was 



made using Sr 87 from lepidolite as carrier 
material. This isotope's purity in the stron- 
tium in lepidolite is so high (99 per cent) 
that it is ideal for the determination of 
small amounts of common strontium. It is 
expected that rubidium-strontium measure- 
ments will be made in the near future on 
the three granites for which lead ages were 
determined. 

Transfer of lead in the Essonville gran- 
ite. Further work on the Essonville granite 
has given evidence of a transfer of lead 
(and possibly uranium and thorium) 
within the minerals of the rock. The 

T'ABLE 12 
Isotopic composition of essonville leads 

Sample 206/204 207/204 208/204 

Perthite from granite 

(observed) 18.4 15.6 39 

Granite composite (cal- 
culated) 16.4 15.3 32 

Perthite from pegma- 
tite (observed) 16.7 15.0 35 

perthite present in the rock contains so 
much lead as compared with uranium and 
thorium that the isotopic composition of 
the lead would not have been affected by 
radioactive decay within the mineral dur- 
ing the billion years the granite has ex- 
isted. Thus it should be the lead present 
when the rock was formed. When one 
compares this measured isotopic composi- 
tion with that calculated from the known 
age and from uranium, thorium, and lead 
data for the rock, it is found that the cal- 
culated ratios of Pb 206 , Pb 207 , and Pb 208 to 
Pb 204 are substantially lower (see table 12). 
This indicates either addition of radio- 
genic lead to the feldspar or else a frac- 
tionation of lead from uranium and tho- 
rium in the rock as a whole. 

In view of this information, a large 
perthite crystal from a pegmatite in the 
Essonville area was analyzed for the iso- 



84 



CARNEGIE INSTITUTION OF WASHINGTON 



208 



topic composition of its lead. Diffusion with high ratios of Pb 206 , Pb 207 , and Pb 

processes should have had much less effect to Pb 204 ) from the sphene of the granite 

here, since the crystal was several centime- with cold 6N hydrochloric acid. Such a 

ters in length. The pegmatite lead agrees process could serve as the source of the lead 

very well with that calculated from the which has been added to the perthite. 

total granite. It is accordingly believed If such transfers of atoms between the 

that there has been no measurable frac- various minerals of granites prove to be 

tionation of uranium, thorium, and lead the general case, the interpretation of age 

in the rock as a whole and that there has measurements based on these minerals will 

been addition of radiogenic lead to the be greatly complicated. The studies of the 

feldspar since it was formed. It is possible coming year should give an indication of 

to leach highly radiogenic lead (i.e., lead how important this factor will be. 



MISCELLANEOUS INVESTIGATIONS 



The system Na 2 — CaO — Si0 2 (Morey). 
Years ago, a fundamental paper on this 
system was published by Morey and 
Bowen (1925, No. 580), and later addi- 
tional results were published by Morey 
(1930, No. 720). In connection with a pa- 
per on the optical properties and densities 
of soda — lime — silica glasses, written in col- 
laboration with Merwin (1932, No. 802), 
a large number of additional mixtures 
were prepared and liquidus determinations 
were made on these mixtures. These re- 
sults, which have not been published, do 
not greatly alter the positions of the bound- 
ary curves. A doubt was cast, however, 
on the existence of the compound Na 2 0* 
2CaO*3Si0 2 , and it is desirable to pub- 
lish the additional proof which has been 
obtained. More experiments should be car- 
ried out in the high-soda part of the sys- 
tem. Some time ago, evidence of the exist- 
ence of a compound of the composition 
Na 2 0*CaO was found, and additional 
work has been done by hydrothermal 
methods on its occurrence. 

New techniques for accurate measure- 
ment of lattice parameters on the powder 
spectrometer (Smith). Two advances in 
practical details have been made. First, it 
has been found that high-accuracy meas- 
urements can be taken from simple smear 



mounts by using thin smears containing a 
calibrating material such as quartz or sili- 
con. Secondly, it has been possible consid- 
erably to reduce the amount of material 
required for the pressed mounts by minor 
variations of the technique described by 
Adams and Rowe (paper in press). 

A systematic method of determining the 
lattice parameters from the observed dif- 
fraction angles has been devised in collabo- 
ration with Chayes. The angles are con- 
verted into (2-values by the method of 
Donnay and Donnay. Qk — ^h%kai, where 
hue are integers appropriate to the ^th re- 
flection and cti are the required lattice pa- 
rameters. If K values of Qk are measured, 
then a set of K simultaneous equations can 
be set up from which the six ais can be de- 
termined. The least-square solution is ob- 
tained by setting up the matrix \hik\, 
computing the corresponding inverse ma- 
trix, and then using this to compute the 
lattice parameters. The inverse matrix was 
kindly calculated for us by the Applied 
Mathematics Division of the National Bu- 
reau of Standards. The two advantages of 
the method are: (1) the most accurate so- 
lution is obtained in a direct systematic 
way, and (2) the same inverse matrix may 
be used for different crystals if they give 
the same measurable X-ray reflections. 



GEOPHYSICAL LABORATORY 



85 



This condition holds for several mineral 
series, such as the plagioclases, to which 
the method is being applied at the mo- 
ment. The use of the same inverse matrix 
eliminates a great deal of tedious compu- 
tation and should result in encouraging 
investigators to make more accurate meas- 
urements of more crystals. 

Field studies of metamorphic roc\s 
(Yoder). In the summer of 1952 the clas- 
sic metamorphosed areas in the Grampian 
highlands of Scotland, the Oslo Fjord re- 
gion in Norway, the Falun region in Swe- 
den, and the Orijarvi region in Finland 
were visited in the company of their most 



distinguished investigators. The major 
purposes of these general surveys were: 
(1) to learn the results of the newer de- 
tailed studies in these and other compara- 
ble regions, (2) to discuss the concept of 
the "water-deficient region" in terms of 
the field observations, (3) to collect series 
of rocks in well established zones of pro- 
gressive metamorphism, and (4) to evalu- 
ate the possibility of carrying out the 
principal metamorphic reactions experi- 
mentally. All purposes were achieved. The 
results will be incorporated in the near 
future with discussions of the program to 
which they apply. 



The "Summary of Published Work" be- 
low briefly describes the papers published 
in scientific journals during the report 
year. In addition, the following papers are 
now prepared for publication: L. H. 
Adams and F. A. Rowe, "The prepara- 
tion of specimens for the focusing-type 
X-ray spectrometer"; L. H. Adams, M. A. 
Tuve, and H. E. Tatel, "Studies of the 
earth's crust using waves from explosions"; 
F. Chayes, "A test of the revised deter- 
minative chart for plagioclase"; F. Chayes, 
"In defense of the second decimal"; F. 
Chayes, "The theory of thin section analy- 
sis"; G. W. Morey, "Hydrothermal syn- 
thesis"; G. W. Morey, "Silica and sili- 



cates"; G. W. Morey, "The binary system 
K4P2O7— KPOs"; G. W. Morey, "The bi- 
nary system NaPOs— KPO3"; G. W. 
Morey, "The system H 2 0— NaPOs"; J. F. 
Schairer, "The system K2O — MgO — Si0 2 : 
I. Results of quenching experiments on 
four joins in the tetrahedron cordierite — 
forsterite — leucite — silica, and on the join 
cordierite — mullite — potash feldspar"; J. V. 
Smith, "Re-examination of the crystal 
structure of melilite"; O. F. Tuttle and 
M. L. Keith, "Quartz and feldspar of a 
Tertiary granite in relation to its thermal 
history"; J. Van den Heurk, "Improved 
hydrothermal quenching apparatus." 



SUMMARY OF PUBLISHED WORK 



(1167) Change of melting point of diopside with 
pressure. H. S. Yoder, Jr. Jour. Geol., 
vol. 60, pp. 364-374 (1952). 

The melting point of synthetic diopside 
under pressures up to 5000 bars was found 
by experiment to be well represented by the 
equation t m = 1391.5 + 0.01297P, where t m is 
the melting point in degrees centigrade and 
P is the pressure in bars. The character of 
the melting curve supports the prevailing 
view that the melting curve rises indefinitely 
with depth in the earth. 



The considerable volume change involved 
in melting is emphasized in a quantitative re- 
view of the process of magma production and 
extrusion. 

(1168) The atomic arrangements and bonds of 

the gold-silver ditellurides. G. Tunell 

and L. Pauling. Acta crystallogr., vol. 5, 

PP- 375-38i (1952). 

The structures of sylvanite, calaverite, and 

krennerite, the three gold-silver ditellurides 

occurring naturally, are basically similar, al- 



86 



CARNEGIE INSTITUTION OF WASHINGTON 



though they have three different space-group 
symmetries. In each of the three minerals the 
gold and silver atoms are surrounded by six 
tellurium atoms, which, however, are not all 
at the same distance. In sylvanite and cala- 
verite, each tellurium atom is surrounded by 
three gold or silver atoms and three tellurium 
atoms. In krennerite, part of the tellurium 
atoms are surrounded by three gold or silver 
atoms and three tellurium atoms, part by one 
gold or silver atom and five tellurium atoms, 
part by five gold or silver atoms and one tel- 
lurium atom. An analysis is given of the 
interatomic distances in terms of the resonat- 
ing-valence-bond theory. 

(1169) A test of the accuracy of chemical analy- 
sis of silicate rocks. H. W. Fairbairn 
and J. F. Schairer. Amer. Mineralogist, 
vol. 37, pp. 744-757 (1952). 

A six-component silicate glass of the pro- 
portions found in granite was prepared and 
its composition controlled so that significant 
errors were eliminated except for Si0 2 (0.02 
per cent) and Al 2 O s (0.01 per cent). Analy- 
sis of this glass by eleven chemical labora- 
tories gave mean values which showed satis- 
factory agreement (<o.i per cent) for MgO, 
CaO, Na 2 0, K 2 0. For Si0 2 and Al 2 O s a 
reciprocal systematic error appeared whereby 
Si0 2 was 0.4 per cent low and A1 2 3 was 0.6 
per cent high; total Si0 2 and A1 2 3 agreed 
almost exactly (<o.i per cent) with the glass 
standard. The practical problem of evaluat- 
ing error in a single analysis is discussed 
briefly in its relation to these results. 

(1170) The system sodium metaphosphate — cal- 
cium metaphosphate. G. W. Morey. Jour. 
Amer. Chem. Soc, vol. 74, p. 5783 
(1952). 

A study of the binary system sodium meta- 
phosphate — calcium metaphosphate showed 
the formation of a compound 2Na 2 0*CaO- 
3P 2 5 with a congruent melting point at 
738 ° C. The eutectic between Na 2 0-P 2 5 
and 2Na 2 ■ CaO ■ 3P 2 5 is at 625 ° and about 
1 per cent CaO-P 2 5 ; that between 2Na 2 0* 
CaO-3P 2 5 and CaOP 2 5 is at 725 ° and 
46 per cent CaO-P 2 5 . 



(1171) The 10 per cent CaAl 2 Si 2 O g plane in the 
system CaSiO s — Ca 2 Al 2 Si0 7 — NaAlSi0 4 
— CaAl 2 Si 2 O s . H. S. Yoder, Jr. Jour. 
Geol., vol. 60, pp. 586-593 (1952). 

The high-temperature equilibrium relations 
in the 10 per cent CaAl 2 Si 2 8 plane in the 
system CaSi0 3 — Ca 2 Al 2 Si0 7 — NaAlSi0 4 — 
CaAl 2 Si 2 8 have been investigated by the 
quenching method. The results contribute to 
the understanding of the origin and differen- 
tiation of alkaline rocks. 

(1172) The flow of glass at room temperatures. 
G. W. Morey. Jour. Optical Soc. Amer., 
vol. 42, pp. 856-857 (1952). 

A 60-inch plane mirror at the Mount Wil- 
son Observatory, which weighed about 2000 
pounds and was 9 inches thick, stood on edge 
for 25 years. A careful study of the surface 
gave no evidence of a distortion's having oc- 
curred as large as a quarter of a wave length 
of light. This affords a convincing demon- 
stration that glass does not flow at ordinary 
temperatures under its own weight. The 
stresses produced by poor annealing, however, 
are probably much greater than those pro- 
duced by the disk, and the consensus of ex- 
perience, empirical though it may be, is that 
glass will flow at room temperatures under 
stresses of the magnitude produced by poor 
annealing. 

(1173) The use of ion exchange columns in 
mineral analysis for age determination. 
L. T. Aldrich, J. B. Doak, and G. L. 
Davis. Amer. Jour. Sci., vol. 251, pp. 
377-387 (1953). 

Ion-exchange columns of synthetic organic 
resins have been found extremely useful in 
the routine separation of the alkali elements 
from those of the alkaline earths in the pro- 
portions in which they are found in potas- 
sium minerals. Complete separation of these 
groups of elements is essential for the mass 
spectrometric analysis of calcium and stron- 
tium in rubidium-containing potassium min- 
erals. Partial separations of rubidium from 
potassium and strontium from calcium 
which increase the relative concentration of 
rubidium and strontium 100-fold are made 



GEOPHYSICAL LABORATORY 



8 7 



without difficulty. The use of suitable com- 
plexing agents for iron and aluminum per- 
mits a high yield of calcium and strontium to 
be obtained from very small samples of iron 
aluminum silicate minerals. 

(1174) List of systems investigated at Geophysi- 
cal Laboratory. L. H. Adams. Amer. 
Jour. Sci., Bowen Volume (vol. 250-A), 
pp. 1-26 (1952). 

The systems investigated at the Geophysi- 
cal Laboratory during the more than forty 
years of its existence have been arranged and 
tabulated, together with the pertinent journal 
references. It is believed that this list, con- 
taining over 300 entries, will be found con- 
venient by students of experimental petrology. 

(1175) The differentiation of a composite aplite 
from the Pribilof Islands, Alaska. T. F. 
W. Barth. Amer. Jour. Sci., Bowen Vol- 
ume (vol. 250-A), pp. 27-36 (1952). 

The mode of occurrence and the field re- 
lations of an aplite intrusion are illustrated. 
The chilled margins show a high content of 
alkalies and silica, but a lower content of 
aluminum, iron, magnesium, and calcium, 
than does the coarse-grained, granular central 
portion. This arrangement may be explained 
on the theory of thermodiffusion as described 
by W. Wahl, whereas crystallization differ- 
entiations would have resulted in the opposite 
arrangement. 

(1176) Chemical petrology of some metamor- 
phosed Adirondack gabbroic, syenitic and 
quartz syenitic rocks. A. F. Buddington. 
Amer. Jour. Sci., Bowen Volume (vol. 
250-A), pp. 37-84 (1952). 

The chemical petrology of 16 metamor- 
phosed Adirondack gabbroic rocks is dis- 
cussed in the light of 15 new chemical anal- 
yses of their minerals, comprising 9 of horn- 
blende, 5 of garnet, and 1 of augite. Four of 
the rock analyses are new. There is a direct 
sensitive correlation between the composition 
of the rocks and the composition of their 
minerals, consistent with an origin through 
mineral reconstitution with little change in 
bulk chemical composition. The nature and 



composition of the minerals also depend on 
whether the rock was reconstituted under 
relatively dry conditions or in the presence 
of hydrous fluids carrying fluorine or chlorine 
or both. 

Chemical aspects of the metamorphism of 
some charnockitic syenitic and quartz syenitic 
rocks are also discussed in the light of new 
chemical analyses of 6 specimens of the major 
rocks, 4 related small pegmatite seams, and 
2 garnets. The pegmatite seams are in large 
part garnetiferous and the product of local 
metamorphic recrystallization with some met- 
amorphic differentiation. 

The metamorphism of the gabbroic, sy- 
enitic, and quartz syenitic rocks occurred in 
connection with regional high-grade dynamo- 
thermal metamorphism, in large part in the 
presence of intergranular films of fluid re- 
lated to a subjacent rising granitic magma. 
The granite magma later intruded the meta- 
morphosed rocks and locally developed a su- 
perimposed reconstitution on the early facies. 
The rocks were in part metamorphosed under 
conditions of the upper temperature range 
for the amphibolite facies and in part in the 
granulite facies. A geologic map showing the 
regional variation in the nature and intensity 
of metamorphism is given. The problem of 
the garnets at the Barton Mine is discussed 
and reasons are given for preferring an origin 
as an aspect of regional metamorphism to an 
origin through local recrystallization directly 
consequent on syenite intrusion, as advocated 
by some other students. 

(1177) Relations between composition and in- 
dices of refraction in natural plagioclase. 
F. Chayes. Amer. Jour. Sci., Bowen Vol- 
ume (vol. 250-A), pp. 85-105 (1952). 

New determinative charts for the refractive 
index-composition relation are presented. Pos- 
sible discontinuities in the relation are dis- 
cussed. Though complete optical continuity 
is not disproved by the data, sample descrip- 
tions based on one or two breaks in the series 
suggest simple relations between the com- 
monly measured natural plagioclases and the 
albite and anorthite polymorphs produced by 
laboratory synthesis. 



88 



CARNEGIE INSTITUTION OF WASHINGTON 



(1178) Two new crystalline phases of the anor- 
thite composition, CaO • A1 2 3 • 2Si0 2 . 
G. L. Davis and O. F. Tuttle. Amer. 
Jour. Sci., Bowen Volume (vol. 250-A), 
pp. 107-114 (i95 2 )- 

Two new crystalline phases of the composi- 
tion CaAl 2 Si 2 8 are described, giving the 
optical properties and X-ray powder diffrac- 
tion data. Their synthesis and stability are 
discussed. Comparisons are drawn with simi- 
lar modifications of BaAl 2 Si 2 O s . 

(1179) The symmetry change in the high-tem- 
perature alkali-feldspar series. G. Don- 
nay and J. D. H. Donnay. Amer. Jour. 
Sci., Bowen Volume (vol. 250-A), pp. 
1 15-132 (1952). 

Accurate unit-cell dimensions are given for 
n synthetic alkali feldspars ranging from 
monoclinic KAlSi 3 8 to triclinic NaAlSi 3 O s . 
Cell edges and angles are plotted against 
composition. The only discontinuity is found 
in the first derivative of the interaxial angle a 
at the point where the change of symmetry 
takes place. No two-phase region was ob- 
served. The phase transition is a high-order 
one, and, for practical purposes, solid solu- 
tion may be considered complete. 

(1180) On the granulites of Lapland. P. Eskola. 
Amer. Jour. Sci., Bowen Volume (vol. 
250-A), pp. 133-171 (1952). 

The granulites of Lapland are garnet-bear- 
ing acid quartz-feldspar rocks, and mostly hy- 
persthene-bearing intermediate, basic, and ul- 
trabasic rocks, the latter forming sharply 
bounded bands in the former. Twenty rock 
analyses and 13 mineral analyses are given, 
and a granulite norm is proposed to show the 
critical minerals of the granulite facies. Spe- 
cific properties of the granulite minerals are 
described. A greater part of the granulites is 
chemically aluminous rock, a fact which sug- 
gests original argillaceous character. Graphite- 
granulites show a composition like that of 
sapropelic sediments; their carbon is supposed 
to be of organic origin. The basic granulites 
are interpreted as metamorphic volcanic or 
hypabyssic rocks, whereas more coarse-grained 



and homogeneous quartz-dioritic rocks are 
assumed to be primary magmatic. The granu- 
lite facies appear to be identical with that fa- 
cies represented by the charnockites, the spe- 
cific characteristics of the foliated granulites 
being due to their tectonic history. 

(1181) Orthopyroxenes of the Bushveld type, 
ion substitutions and changes in unit cell 
dimensions. H. H. Hess. Amer. Jour. 
Sci., Bowen Volume (vol. 250-A), pp. 
173-187 (1952). 

The a, b, and c dimensions of the unit cell 
of a number of orthopyroxenes of the Bush- 
veld type were measured. The variation in 
size with substitution of Fe +2 for Mg +2 and 
Al +3 for Mg +2 and Si +4 are given. The optical 
properties N e> 2V, and birefringence have 
been revised and density determinations made 
on a number of samples. For ordinary ortho- 
pyroxenes of the Bushveld type with 2% 
per cent R 2 3 , unit cell dimensions, N z , bire- 
fringence, and density vary as linear func- 
tions within the limits of accuracy of the ob- 
servations, and thus appear to obey Vegard's 
law. The quantities present of all of the main 
constituents of these pyroxenes, magnesium, 
iron, aluminum, and calcium, can be deter- 
mined from optical property and unit cell 
measurements without chemical analysis. It 
is suggested that, other things being equal, 
the aluminum content may increase with 
pressure and should be further investigated 
as a potential means of assessing depth of 
crystallization. 

(1182) Twinning frequency in feldspar pheno- 
crysts from a quartz latite sill at Sierra 
Blanca, Texas. E. Ingerson. Amer. Jour. 
Sci., Bowen Volume (vol. 250-A), pp. 
189-202 (1952). 

Study of some 1500 sanidine phenocrysts 
from a quartz latite sill in Texan Moun- 
tain, Trans-Pecos, Texas, shows the following 
abundances of (1) untwinned crystals, (2) 
Carlsbad, (3) Manebach, and (4) Baveno 
twins, respectively: from a zone near the up- 
per contact, (1) 84.35 per cent, (2) 8.5 per 
cent, (3) 6.9 per cent, (4) 0.25 per cent; from 



GEOPHYSICAL LABORATORY 89 

the center of the sill, (1) 94.3 per cent, (2) version studies on synthetic quartz. For ex- 

3.3 per cent, (3) 2.4 per cent, (4) not ob- ample, synthetic quartz grown in the pres- 

served. The average size of the phenocrysts ence of germanium has an inversion break 

near the top of the sill is larger than that of 40 ° C above the normal range for quartz, 

those near the center; the twinned crystals whereas quartz grown in the presence of 

are significantly larger than the untwinned lithium and aluminum has the inversion tem- 

ones in both places. These facts are tenta- perature lowered by as much as 120 ° C. Spec- 

tively explained as due to (1) somewhat trochemical analysis of natural quartz with 

earlier initiation of crystallization of twinned different inversion temperatures shows varia- 

crystals, (2) floating of early-formed pheno- tions in the amounts of minor elements, and 

crysts, and (3) greater tendency for nuclei to this variation is in turn accompanied by 

develop twinning in the more disturbed con- changes in the cell dimensions as measured by 

tact zones. Spectrographic and chemical anal- X-ray methods. 

yses show significantly more rubidium and The amount of solid solution is influenced 

lithium in the untwinned and more of the al- by the temperature of growth, and therefore 

bite molecule in the twinned crystals. Both the inversion temperature can be used as an 

these relations would be expected if the indication of the relative temperature of for- 

twinned crystals started forming earlier and mation of samples of quartz which grew in 

at a higher temperature than the untwinned similar chemical environments. A general 

ones. relation between the inversion temperatures 

and the occurrence of natural quartz is de- 

(1183) Significance of variation in the high-low rived from comparison of occurrences for 

inversion of quartz. M. L. Keith and which approximate formation temperatures 

O. F. Tuttle. Amer. Jour. Sci, Bowen can De inferred. For example, quartz from 

Volume (vol. 250-A), pp. 203-280 (1952). rhyoliteS) where the presence o£ g l ass indi . 

The high-low quartz inversion of some 250 cates high temperature, inverts at lower tem- 

quartz specimens has been studied by a dif- peratures than quartz from veins or from 

ferential thermal method. The method does cavities in limestone, where geologic evidence 

not permit determining the exact temperature indicates a lower temperature of formation, 

at which the inversion would take place un- There are, however, numerous exceptions 

der equilibrium conditions, but the measured to this relationship, and the temperature dif- 

temperature is probably not greatly different ferences in the inversion can generally be 

from the equilibrium value. The difference taken to indicate only that the quartz is in 

between the inversion temperatures of various some way different. In other words, the in- 

quartz specimens can, however, be deter- version can in most cases be used only as a 

mined to within ±o.i° C when the heat ab- "fingerprint" method of comparing quartz 

sorption is rapid (approximately 90 per cent from various sources and for the study of zon- 

of all specimens studied). ing within rock bodies; in these applications 

Differences between the inversion tempera- it has proved to be potentially useful. A large 

tures of natural quartz samples vary over a proportion of the present report is a prelimi- 

range of 38 ° C, and the inversion of synthetic nary "fingerprinting" of quartz from various 

quartz varies over a range of 160 C. Over rock types. 
95 per cent of all natural specimens examined, 

however, invert on heating within a range (1184) Japanese twins of quartz. S. Kozu. 

of 2.5 ° C. Amer. Jour. Sci., Bowen Volume (vol. 

Variations found in the inversion tempera- 2 5°-A), pp. 281-292 (1952). 

ture are believed to be the result of solid solu- The possible types of quartz twins which 

tion of small amounts of ions other than Si 4+ incorporate the "Japanese twin" law are enu- 

and O 2- . This conjecture is supported by in- merated. Etching was used to determine the 



9 o 



CARNEGIE INSTITUTION OF WASHINGTON 



twin law and composition plane. Differences 
in the crystals are related to their genetic 
conditions. 

(1185) Thermochemistry of plagioclase and al- 
kali feldspars. F. C. Kracek and K. J. 
Neuvonen. Amer. Jour. Sci., Bowen Vol- 
ume (vol. 250-A), pp. 293-318 (1952). 

Employing a hydrofluoric acid solution cal- 
orimeter, previously described, measurements 
of the heats of solution (decomposition) were 
performed in 20 per cent hydrofluoric acid at 
74.7 ° C for 21 feldspar materials in the 
plagioclase and alkali feldspar series. In com- 
bination with other pertinent measurements, 
these will lead to evaluation of the heats of 
formation of the feldspars. The results pre- 
sented in this paper show that plagioclase 
feldspars in their natural state exist not as 
the simple, continuous solid-solution series 
that is found at the liquidus, but rather fall 
into three groups with dividing lines drawn 
at 30 and 65-70 mole per cent anorthite. The 
intermediate labradorite compositions appear 
to be mixtures of feldspars of the limiting 
compositions indicated. The alkali feldspars 
have thermal properties highly dependent on 
their origin and thermal history. Values of 
the latent heats of melting of albite and 
anorthite have been deduced from the ther- 
mochemical measurements. The average val- 
ues are 49.2 cal/g for albite and 64.7 cal/g 
for anorthite. The heat of inversion of low, 
natural albite to high-temperature albite is 
13 cal/g. 

(1186) The effect of temperature on the sym- 
metry of high-temperature soda-rich feld- 
spars. W. S. MacKenzie. Amer. Jour. 
Sci., Bowen Volume (vol. 250-A), pp. 
319-342 (1952). 

X-ray and optical data show that natural 
anorthoclase and synthetic soda-rich feldspars, 
triclinic at room temperature, acquire mono- 
clinic symmetry on heating. On cooling, the 
reverse process takes place. The experimental 
results suggest that there are two triclinic 
forms of synthetic high-albite and adjacent 
feldspars. The temperature at which the sym- 
metry becomes monoclinic differs in the two 



forms, and there are slight differences in the 
X-ray powder diffraction patterns at room 
temperature. 

The inversion temperatures of natural an- 
orthoclases may prove useful in geologic ther- 
mometry. 

(1187) The system H 2 0— Na 2 0— Si0 2 at 400 ° C. 
G. W. Morey and J. M. Hesselgesser. 
Amer. Jour. Sci., Bowen Volume (vol. 
250-A), pp. 343-371 (1952). 

A method and an apparatus have been de- 
vised which have made possible the analysis 
of coexisting gas and liquid phases in the 
system H 2 — Na 2 — Si0 2 at 400 ° C and at 
pressures up to 2500 bars. The isothermal 
polybaric saturation curves — both gaseous and 
liquid — of quartz, sodium disilicate, and so- 
dium metasilicate have been determined, and 
the melting pressure of Na 2 • 2Si0 2 has been 
found to be 2200 bars. The boundary curve 
G + L '+ quartz + sodium disilicate is con- 
tinuous and does not intersect the critical end- 
point curve, and probably the boundary curve 
G + L + sodium disilicate + sodium meta- 
silicate has a similar relationship. There are 
probably two critical regions surrounded by 
critical curves, one of which is represented by 
(G = L) + Na 2 0-Si0 3 , the other by (G = 
L) + Na 2 0*2Si0 2 , although the possibility 
has not been excluded that these two critical 
curves intersect, giving rise to a double criti- 
cal end point (G = L) + Na 2 OSi0 2 + 
Na 2 # 2Si0 2 . There is also a critical region 
represented by (G = L) + Qtz. 

(1188) Heat of formation of merwinite and 
monticellite. K. J. Neuvonen. Amer. 
Jour. Sci., Bowen Volume (vol. 250-A), 
PP. 373-38o (1952). 

The heats of formation of merwinite, 
Ca 3 Mg(Si0 4 ) 2 , and monticellite, CaMgSi0 4 , 
have been measured by means of solution 
calorimetry. Natural merwinite from Crest- 
more, California, and natural monticellite 
from Magnet Cove, Arkansas, were used for 
the measurements. The results, corrected for 
theoretical compositions of the two minerals, 
are for merwinite AH = —57,020 ±380 cal/ 
mole and for monticellite AH = — 27,560 ± 



GEOPHYSICAL LABORATORY 



91 



140 cal/mole. The values account for the 
heat of formation of the two silicates at 25 ° C 
from quartz, calcium oxide, and magnesium 
oxide (prepared by dehydrating magnesium 
hydroxide 2.5 hours at 1425 C). 

(1189) The chemistry of the Keweenawan lavas. 
P. Niggli. Amer. Jour. Sci., Bowen Vol- 
ume (vol. 250-A), pp. 381-412 (1952). 

Research by various authors and especially 
by T. M. Broderick and Henry R. Cornwall 
has done much to clarify the chemistry of the 
Keweenawan lavas. Calculations and graphic 
representations based on molecular units in- 
stead of weight percentages are carried out in 
the present paper with a view to clarifying 
the differentiation tendencies in these basic 
magmas. It is pointed out that the formation 
of the so-called pegmatite layers can be re- 
garded as the first indication of a differentia- 
tion tending toward the development of a 
spilitic to keratophyric association. 

(1190) The system diopside — forsterite — anor- 
thite. E. F. Osborn and D. B. Tait. 
Amer. Jour. Sci., Bowen Volume (vol. 
250-A), pp. 413-433 (1952). 

The system diopside — forsterite — anorthite 
is an example of a system containing a pyrox- 
ene, an olivine, and a feldspar in which vir- 
tually no solid solution or reaction relation 
among the phases exists. This system, how- 
ever, may be considered to be one face of a 
tetrahedron representing the system diopside 
— forsterite — anorthite — silica, which is note- 
worthy for crystal-liquid reaction phenomena 
as liquids crystallize under equilibrium condi- 
tions. Phase-equilibrium data are presented, 
and their bearing on the crystallization of 
spinel from basaltic liquids and on the forma- 
tion of coronite is discussed. 

(1191) A reconnaissance of liquidus relations in 
the system K 2 0*2Si0 2 — FeO — Si0 2 . E. 
Roedder. Amer. Jour. Sci., Bowen Vol- 
ume (vol. 250-A), pp. 435-456 (1952). 

A reconnaissance has been made of that 
portion of the system K 2 — FeO — Si0 2 hav- 
ing K 2 0:Si0 2 ratios greater than 1:2. The 
results on 62 compositions are presented as a 
preliminary phase diagram for the condensed 



subsystem K 2 • 2Si0 2 — FeO — Si0 2 , repre- 
senting liquidus relations in equilibrium with 
metallic iron under one atmosphere pressure 
of pure nitrogen. Two new compounds, 
K 2 0-FeO-3Si0 2 and K 2 • FeO • 5Si0 2 , were 
found, and their relations to equivalent com- 
pounds in the systems K 2 — A1 2 ; , — Si0 2 
and K 2 — MgO — Si0 2 discussed. 

(1192) Leucite, potash nepheline, and clino- 
pyroxene from volcanic lavas from south- 
western Uganda and adjoining Belgian 
Congo. Th. G. Sahama. Amer. Jour. 
Sci., Bowen Volume (vol. 250-A), pp. 
457-470 (1952). 

Four specimens of rocks from the young 
volcanic belt of southwestern Uganda and 
adjoining Belgian Congo have been investi- 
gated. Leucite, nepheline, and clinopyroxene 
(diopside), extracted from the rocks by means 
of heavy liquids, have been analyzed chemi- 
cally. Optical properties are also given. 
Chemical compositions of the analyzed min- 
erals are discussed. 

(1193) The system FeO— A1 2 3 — Si0 2 . J. F. 
Schairer and K. Yagi. Amer. Jour. Sci., 
Bowen Volume (vol. 250-A), pp. 471- 
512 (1952). 

Phase-equilibrium studies of this system, at 
and just below temperatures where a liquid 
phase is present, show one ternary compound, 
the iron analogue of cordierite (2FeO* 
2Al 2 3 , 5Si0 2 ), which decomposes at 1210 
±io° C to mullite, tridymite, and liquid. 
The fields of stability of corundum, mullite, 
hercynite, iron cordierite, cristobalite, tridy- 
mite, fayalite, and wiistite have been deline- 
ated. The following invariant points (the 
first two eutectics, and the remainder reaction 
points) were located: fayalite + wiistite -f- 
hercynite + liquid, ii48°±5°; fayalite + 
iron cordierite + tridymite + liquid, 1083 
it 5 ; fayalite + iron cordierite + hercynite 
+ liquid, io88°±5°; hercynite + iron cor- 
dierite + mullite + liquid, i205°±io°; 
iron cordierite + mullite + tridymite + 
liquid, 1210 ±io°; corundum + mullite 
+ hercynite + liquid, i38o°±5°; cristo- 
balite + tridymite + mullite + liquid, 

o . o 

1470 ± 10 . 



9 2 



CARNEGIE INSTITUTION OF WASHINGTON 



Iron cordierite crystallizes with some re- 
luctance, and the metastable invariant points 
fayalite + tridymite + spinel + liquid at 
io73°±5° and mullite + hercynite + tridy- 
mite + liquid at 1205 ° ±io° can be realized. 
No ferrosilite or almandine garnet could be 
crystallized from the melts at any tempera- 
ture, even when melts were seeded with these 
crystalline phases. Natural almandine from 
Botallack, England (91.3 per cent almandine) 
when heated begins to decompose at an ap- 
preciable rate as low as 900 ° C, and yields a 
mixture of hercynite, iron cordierite, and fa- 
yalite. The bearing of these results on petrol- 
ogy and slags is discussed. 

(1194) Single-crystal measurements on paracel- 
sian. J. V. Smith. Amer. Jour. Sci., 
Bowen Volume (vol. 250-A), pp. 513- 
515 (1952). 

The cell dimensions and space group of 
paracelsian have been determined, and have 
been compared with those of topaz and dan- 
burite. There is a close similarity between 
paracelsian and danburite. 

(1195) Temperature scales and silicate research. 
R. B. Sosman. Amer. Jour. Sci., Bowen 
Volume (vol. 250-A), pp. 517-528 (1952). 

The temperature scale for the range 300 ° C 
to the melting point of platinum, used by the 
Geophysical Laboratory from 19 12 to the 
present, was based on the nitrogen thermome- 
ter work of Day and Sosman. The first 
International Temperature Scale (1927) was 
a thermodynamic scale, with fixed points a 
little higher than those of Day and Sosman. 
The revision of the I. T. S. adopted in 1948, 
by raising the value of the constant in the 
Wien-Planck law of radiation, brings the 
high-temperature scale nearer to the Geo- 
physical Scale. Curves show the differences 
between the Geophysical and the I. T. S. of 
1927 and 1948. 

(1196) Some trends of basaltic magma in lime- 
stone syntexis. C. E. Tilley. Amer. Jour. 
Sci., Bowen Volume (vol. 250-A), pp. 
529-545 (1952). 

The trend of basaltic magma consequent 
on limestone reaction is considered in the 



light of new data from the contact zones of 
Camas M6r, Muck, and Scawt Hill, County 
Antrim, in the British Tertiary igneous prov- 
ince. The chain of reaction products — meli- 
litic theralites, melilitic nepheline dolerites, 
and the derivative nepheline dolerites — ex- 
presses the trend of a residual liquid in which 
the concentration of iron relative to magnesia 
is strongly emphasized. In this and other 
features these assemblages present a contrast 
to the more common mafic alkali rocks of 
the type of nepheline basalt, nephelinite, and 
their melilitic and monticellite-bearing varie- 
ties. Some reference is made to the genetic 
features of these latter rocks and to the prob- 
lem of the desilication of granitic liquid by 
limestone syntexis. 

(1197) The angle between the #-axis and the 
trace of the rhombic section on the 
(oio)-pinacoid in the plagioclases. G. 
Tunell. Amer. Jour. Sci., Bowen Volume 
(vol. 250-A), pp. 547-551 (1952). 

The angle between the a-axis and the 
trace of the rhombic section on the {010}- 
pinacoid is given in terms of y, the angle 
between the tf-axis and the £-axis, and the 
angle between the {ooi}-pinacoid and the 
(oio)-pinacoid by the formula 

cos (001 A 010) 



cot o = 



cot y 



Values of a for a number of plagioclases from 
pure albite to pure anorthite were calculated 
from the interaxial angles of Wiilfing by 
means of this formula. The values of o for 
these plagioclases calculated from the inter- 
axial angles of Wiilfing by Rosenbusch and 
Miigge were computed by means of an incor- 
rect formula. 

(1198) Optical studies on alkali feldspars. O. F. 
Tuttle. Amer. Jour. Sci., Bowen Volume 
(vol. 250-A), pp. 553-567 (1952). 

Optical properties of alkali feldspar pheno- 
crysts from extrusive rocks place these feld- 
spars, sanidines, and anorthoclases in a series 
with high-temperature albite as the soda end 
member. This information, together with the 
results of Spencer (1937), permits classifying 
the alkali feldspars into four series. 



GEOPHYSICAL LABORATORY 



93 



(1199) The MgO— A1 2 3 — Si0 2 — H 2 system 
and the related metamorphic facies. 
H. S. Yoder, Jr. Amer. Jour. Sci., Bowen 
Volume (vol. 250-A), pp. 569-627 (1952). 

Equilibria in a portion of the system MgO 
— ALO3 — Si0 2 — H 2 have been determined 
at temperatures from 430 ° to 990 ° C at pres- 
sure of water vapor up to 30,000 pounds per 
square inch. The univariant pressure-temper- 
ature curves have been bracketed for the fol- 
lowing reactions: brucite + clinochlore ^ 
forsterite + spinel + vapor, talc + clino- 
chlore <=± forsterite + cordierite + vapor, 
clinochlore ^± forsterite + cordierite + spi- 
nel + vapor; and some of the previously in- 
vestigated reactions in the MgO — SiOo — H 2 
system are confirmed. 

A new low-temperature form having the 
clinochlore composition was prepared, but its 
stability has not been fixed with certainty. 
It is suspected that this form may be isostruc- 
tural with one form of serpentine. Pyrope 
was not synthesized, and natural pyrope was 
not found to be stable in the presence of an 
excess of water vapor in the pressure and 
temperature range investigated. Amesite and 
magnesian chamosite were not produced. 
Metastable growth of many of the phases 
occurring in the system is common, and they 
survive long periods of time. 

The phase assemblages obtained in equi- 
librium with vapor are summarized at sig- 
nificant temperature intervals at 15,000 psi. 
These assemblages outline compositions in the 
system for which water is prohibited as a 
stable phase. The conclusion is reached that 
the presence of an "excess" or "deficiency" 
of water vapor greatly influences the mineral- 
ogy of a metamorphic rock. On this basis, 
it is demonstrated that all the now accepted 
critical assemblages which define the meta- 
morphic facies may have formed under the 
same pressure and temperature conditions, 
the different facies being primarily a func- 
tion of the bulk composition. A new set of 
critical assemblages indicative of significant 
pressure and temperature conditions is re- 
quired for the various stages in progressive 
metamorphism. In addition, it is shown that 



a common hydrothermal alteration which has 
been interpreted as retrograde metamorphism 
need not mean a change in pressure or tem- 
perature conditions, but may mean an access 
of water vapor. 

(1200) Bowen Volume, American Journal of 
Science, vol. 250-A. viii + 627 pp. (1952). 

Bound volume comprising papers nos. 1174 
through 1 199. 

(1201) A note on the stability of jadeite. L. H. 
Adams. Amer. Jour. Sci., vol. 251, pp. 
299-308 (1953). 

By use of certain simplifying assumptions, 
the stability pressure, at various temperatures, 
for the formation of jadeite from nepheline 
and albite is calculated from thermal data. 
The pressure increases by about 18 bars per 
degree; and at 400 ° C the pressure is esti- 
mated to be 4800 bars. From the known be- 
havior of hydrates under high pressure it is 
suggested that under pressure analcite may 
melt incongruently to form jadeite and water, 
so that at a sufficiently high pressure jadeite 
rather than analcite would be produced from 
a mixture of the correct composition, even 
in the presence of excess water. 

(1202) Polymorphism. F. C. Kracek. Encyclo- 
paedia Britannica, vol. 18, pp. 187^-188 
(1953 copyright). 

A review of polymorphism in its classic 
aspects. 

(1203) The relation between area and volume in 
micrometric analysis. F. Chayes. Min- 
eralogical Mag., vol. 30, pp. 147-149 
0953). 

The validity of a modal analysis as an 
estimate of the composition by volume of the 
parent rock has nothing to do with the fact 
that it is also, and quite inadvertently, an 
estimate of the composition by volume of the 
thin section on which it is made. The only 
role of the thin section is to provide a surface 
on which the areas of the phases can be meas- 
ured, and in this respect, its only advantage 
over an opaque polished surface arises from 



94 



CARNEGIE INSTITUTION OF WASHINGTON 



the ease and accuracy with which the phases 
can be identified by transmitted light. 

The basic relation between area and vol- 
ume in micrometric analysis seems to have 
been clearly understood by Delesse. In intro- 
ducing the method more than a century ago, 
he stated very firmly that no attempt should 
be made to "see into" the rock; measure- 
ments were to be confined to surface areas. 
His demonstration is based largely on geo- 
metric intuition, and the intuition of succeed- 
ing generations of petrographers has not been 
so clear as his. The lack of adequate analyti- 
cal proof has been responsible for much sub- 
sequent confusion. 

(1204) Research in experimental geology at the 
Geophysical Laboratory. J. F. Schairer. 
Capital Chemist, vol. 3, pp. 130-133 
(i953). 
This paper, prepared for the May 1953 is- 
sue of the Capital Chemist, which featured 
the Geophysical Laboratory, broadly sketches 
the Laboratory's history and major accom- 
plishments. Emphasis is placed on the quan- 
titative approach through experimental ap- 
plication of chemistry, physics, physical chem- 
istry, and thermodynamics to geologic prob- 
lems concerning the nature and formation of 
igneous and metamorphic rocks. Before such 
studies could be properly undertaken, the 
necessary apparatus and methods had to be 
developed. Among these preliminary efforts 
were the establishment of a standard tempera- 
ture scale for temperatures at least up to 
1755 ° C and the development of the method 
of quenching for the accurate determination 
of phase-equilibrium relations. Since silica is 
one of the major constituents of the earth's 
crust, much of the Laboratory work has in- 
volved study of polycomponent silicate sys- 
tems, both anhydrous and hydrous. From 
these studies, our knowledge of the melting 
and crystallization relations of the various 
minerals has been established and extended. 
In addition, valuable data immediately ap- 
plicable to industrial purposes have been ob- 
tained. For example, contributions have been 
made directly to the Pordand cement, glass, 



ceramic, steel, and metallurgical industries. 
The chemist and physicist have gone into the 
field with the geologist to learn his problems 
and then have set about to find some of the 
answers through an experimental approach. 

(1205) Annual report of the Director for 195 1- 
1952. 

(1206) Petrochemical studies on the alkalic rocks 
of the Morotu district, Sakhalin. K. Yagi. 
Bull. Geol. Soc. Amer., vol. 64, pp. 769- 
809 (i953)- 

The alkalic rocks of the Morotu district 
occur as sheets, laccoliths, and dikes in the 
Tertiary formations and are probably Plio- 
cene. The rocks vary from dolerite, the most 
abundant, through monzonite to syenite. 
Most of the intrusive bodies, except small 
sheets and dikes, are composed of dolerite in 
the marginal parts and monzonite or syenite 
or both in the central parts, with gradational 
boundaries. Monzonite and syenite also occur 
as irregular veinlets or schlieren in the doler- 
itic parts, with sharp boundaries. Thus differ- 
entiation in situ is strikingly displayed. These 
intrusive bodies are, therefore, formed by 
composite intrusion. Contact effects of the 
intrusions on the Tertiary formations are 
weak and are confined to the immediate con- 
tact zone. Phenomena of assimilation have 
not been observed. 

Principal minerals of these rocks are plagio- 
clase, anorthoclase, microperthite, olivine, ti- 
tan- and alkali-pyroxenes, alkali-amphiboles, 
titanbiotite, analcite, and iron ores. Feldspar 
evolves from labradorite to oligoclase and is 
joined by anorthoclase and microperthite in 
the later stage. The trend is always toward 
enrichment in the orthoclase molecule. Py- 
roxene, the most important mafic mineral, 
forms a continuous reaction series from diop- 
sidic augite through titanaugite, soda-augite, 
and aegirinaugite to aegirine. Amphibole also 
forms a reaction series from barkevikite 
through kaersutite and hastingsite to arfved- 
sonite, but it is not clear whether their relation 
is continuous or discontinuous. Biotite is 
abundant in the dolerites, but very low in the 
syenites. Analcite is abundant in all rocks, 



GEOPHYSICAL LABORATORY 



95 



apparently formed hydrothermally in the later 
stages. 

Chemically these rocks range from 46 to 
61 per cent Si0 2 . Their alkali-lime index is 
50.0, placing the suite in the "alkalic series." 
The parental magma is inferred to have been 
olivine basaltic magma with moderately al- 
kalic affinity. The various rock types are 
believed to have been formed chiefly by crys- 
tallization differentiation from the parental 
magma after it intruded into the present posi- 
tion. Volatile components have also played 
an important role during crystallization, espe- 
cially in the later stage. 

There is no absolute enrichment in iron 
throughout the crystallization course of the 
Morotu rocks. It is inferred that not only the 
shape of the intrusive bodies, but also the 
composition of the parental magma deter- 
mines whether iron enrichment or alkali and 
silica enrichment will prevail in the intrusive 
bodies. 



Its geographical position, its period of ac- 
tivity, and its petrological character justify the 
conclusion that the Morotu district constitutes 
the northeastern end of the Circum-Japan Sea 
province of Cenozoic alkalic rocks. 

(1207) The crystal structure of paracelsian, 
BaAl 2 Si 2 O g . J. V. Smith. Acta crystal- 
logr., vol. 6, pp 613-620 (1953). 

Paracelsian, BaAl 2 Si 2 8 , is isostructural with 
danburite, CaB 2 Si 2 8 , whose structure is sim- 
ilar to that of the feldspars. It is monoclinic 
but very nearly orthorhombic. The struc- 
ture was determined by two-dimensional 
Fourier methods. Fairly accurate dimensions 
of the barium polyhedra were obtained. The 
value for the mean distance Sii /2 Ali /2 -0 is 
of interest. Correlation with recent values for 
Si-O, Si 3 / 4 Al 1 /4-0 suggests values of i.6o 5 A 
for Si-O and 1.78 + 0.02 A for Al-O. The 
latter value agrees well with the sum of the 
Goldschmidt radii but is larger than the sum 
of the Pauling radii. 



BIBLIOGRAPHY 



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The relation between area and volume 

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Doak, J. B. See Aldrich, L. T. 

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9 6 



CARNEGIE INSTITUTION OF WASHINGTON 



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Sosman, R. B. Temperature scales and silicate 
research. Amer. Jour. Sci., Bowen Volume 
(vol. 250-A), pp. 517-528 (1952). 

Tait, D. B. See Osborn, E. F. 

Tilley, C. E. Some trends of basaltic magma 
in limestone syntexis. Amer. Jour. Sci., 
Bowen Volume (vol. 250-A), pp. 529-545 
(1952). 

Tunell, G. The angle between the a-axis and 
the trace of the rhombic section on the 
(oio)-pinacoid in the plagioclases. Amer. 
Jour. Sci., Bowen Volume (vol. 250-A), pp. 

547-551 (1952). 

and L. Pauling. The atomic arrange- 
ments and bonds of the gold-silver ditel- 
lurides. Acta crystallogr., vol. 5, pp. 375- 
381 (1952). 

Tuttle, O. F. Optical studies on alkali feldspars. 
Amer. Jour. Sci., Bowen Volume (vol. 
250-A), pp. 553-567 (1952). 

See Davis, G. L.; Keith, M. L. 

Yagi, K. Petrochemical studies on the alkalic 
rocks of the Morotu district, Sakhalin. Bull. 
Geol. Soc. Amer., vol. 64, pp. 769-809 

(i953). 

See Schairer, J. F. 

Yoder, H. S., Jr. Change of melting point of 
diopside with pressure. Jour. Geol., vol. 60, 
pp. 364-374 (1952). 

The 10 per cent CaAl 2 Si 2 8 plane in 

the system CaSiO s — Ca 2 Al 2 Si0 7 — NaAlSi0 4 
— CaAl 2 Si 2 8 . Jour. Geol., vol. 60, pp. 586- 

593 (1952). 

The MgO— A1 2 3 — Si0 2 — H 2 system 

and the related metamorphic facies. Amer. 
Jour. Sci., Bowen Volume (vol. 250-A), pp. 
569-627 (1952). 



DEPARTMENT OF TERRESTRIAL MAGNETISM 

Washington, D. C. 
MERLE A. TUVE, Director 

Several items of particular interest and our nuclear physicists have elected to de- 
satisfaction are included in the following vote themselves to the understanding and 
report, which is in effect a running account experimental clarification of biological 
of one year of work by the physicists who problems is only an illustration of the char- 
comprise the stafT of this Department, acter of basic research. Strict lines of de- 
Their work is not directed toward the ex- marcation no longer exist between subjects 
ploration of a selected set of particular of study when the mode of approach is that 
mysteries connected with the earth's mag- of fundamental science. Physics is a mother 
netism, although problems in this area are subject for a whole range of specialized 
not ignored. inquiries. It is encouraging to find in this 

The work of the investigators at the De- age of great specialization that many of 

partment today is the present expression of the keenest minds in basic research in vari- 

a policy on basic research evolved through ous laboratories no longer accept the tra- 

several decades. The original plans of the ditional restriction of their research interest 

Department for a magnetic survey of the and activity to a single narrow set of ques- 

earth led in a few years to the formulation tions, but are viewing their own special 

of some basic questions about the structure advances in the perspective of a whole 

of the earth and its atmosphere, and the range of related and active research areas, 

various observed effects of the sun. By the Research, as a professional activity, is 

middle twenties the conviction grew that vastly different in this mid-century decade 

a healthy program on basic questions in from the minor adjunct of university and 

geophysics could best be fostered by having hospital programs which it was in the 

a group of laboratory physicists concerned United States when the Carnegie Institu- 

with fundamental problems, such as nu- tion and this Department were organized 

clear physics, working in close daily as- shortly after 1900. The great proliferation 

sociation with the men concerned with the of research and development laboratories 

geophysical questions. in industrial establishments, colleges, uni- 

About half the staff members are ac- versities, and agencies of government 

tively directing their efforts toward fur- which took place during and just after 

ther illumination of matters relating to the World War II has brought into unmis- 

physical and geological history of the earth takably prominent relief the question 

or to the state of the upper atmosphere, or whether direct contribution to a selected 

to solar and cosmic influences observed on technical task or subject, such as terrestrial 

the earth. These investigators are chiefly magnetism, is in fact the most fruitful 

men whose training and part of whose type of contribution the Institution may 

efforts are concerned with modern labora- attempt to foster, a question to which our 

tory physics, and their daily companions, experience in previous decades had given 

at lunch and in seminar discussions, are at least a partially negative answer. The 

men who are intensively working on lab- staff of the Department undertakes in- 

oratory problems. The fact that several of stead to make a continuous evaluation of 

97 



9 8 



CARNEGIE INSTITUTION OF WASHINGTON 



the most creative and fruitful activities 
they can individually carry on as physi- 
cists devoted to fundamental research, 
moving forward of course from their own 
special fields of training and interest, and 
hence with a natural bias toward geophysi- 
cal problems. This evaluation and guid- 
ance of emphasis is not made in any de- 
tached or distant fashion, but by actually 
living and thinking and working together, 
individually dedicating their efforts to 
problems in their own fields of compe- 
tence which seem both important and 
approachable, but without undue preoc- 
cupation with some preselected and highly 
specific topic. 

The continuing value of such an evolv- 
ing and experimental example of a small 
and traditional research laboratory, as con- 
trasted with the expansive and highly goal- 
directed activities which receive such em- 
phasis in the physics departments of our 
universities today, is clear to anyone who 
quietly contemplates the present confusion 
of physics with technology and the wide- 
spread public misconceptions which em- 
phasize utility as the aim of basic research. 
The latter error appears in some measure 
to be connected with the budget defense 
of large-scale activities. 

Research here is regarded as a highly 
personal activity, not a large-scale effort 
for a team. There are important values 
for each investigator, however, in the stim- 
ulus of close association with a few other 
intensely active and interested research 
men, several of them usually working on 
problems closely akin to his own, others 
equally active and enthusiastic about prob- 
lems in a widely different area, so that in 
the course of each week or two he encoun- 
ters the fresh stimulus of new ideas or re- 
search progress in a whole range of scien- 
tific fields. This is a satisfying way for a re- 
search man to live, and it is fruitful. A 
concrete object lesson to the staff members 



and to many visitors has been the striking 
contrast between the actual operations here 
and current notions about "team research" 
and the supposed necessity for a research 
man to be extremely specialized and nar- 
row in all his interests and thinking. 

The nuclear physics men who have con- 
cerned themselves with measuring radio- 
active isotope relationships by means of 
the mass spectrograph have found stron- 
tium-rubidium ratios in the minerals sepa- 
rated from rocks collected in New Mexico, 
Colorado, and Wyoming which show, if 
isotope ratios are reliable measures of age, 
that these rocks were laid down about 3400 
million years ago. Certain parts of Canada, 
Africa, and Scandinavia have long been 
known as areas of the most ancient igne- 
ous activity, and their minerals show ages 
of the same magnitude. It will be a sur- 
prise to many that rocks of such extreme 
apparent age are found among the granites 
and pegmatites of the Rocky Mountains. 

There has been an unexpected develop- 
ment of new evidence concerning the im- 
portance of atmospheric circulation and 
zonal winds in the production of magnetic 
storms. The further elaboration of the dy- 
namo theory, made possible by modern 
studies of winds in the upper atmosphere, 
coupled with recent revisions in our under- 
standing of the electrical conductivity of 
the ionosphere overhead, now indicates 
that the electric currents which produce 
magnetic storm effects are primarily in 
the atmosphere, and the wind motions 
which produce them are initiated by radia- 
tions and perhaps by particles from the 
sun. 

Other items of growing future interest 
concern developments in radio astronomy, 
and measurements on the pathways in 
living things by which inorganic carbon 
is incorporated to form particular groups 
of amino acids and amino acid residues 
in proteins and nucleic acids. 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



99 



It may well be imagined that the dis- basic research in the physical sciences to- 

cussions of the physicists who are sharing day. It is hoped that this report, in addi- 

ideas and hopes and successes and disap- tion to presenting factual material, may 

pointments as they work together here also serve as some indication of the 

illustrate in a modest but personal way the variety and the friendly intensity of those 

stimulus and satisfaction connected with discussions. 



EXPERIMENTAL GEOPHYSICS 



RADIO ASTRONOMY 

R. J. Britten, L. Owren, F. G. Smith, H. E. 
Tatel, M. A. Tuve, and H. W. Wells 

For nearly thirty years the Department 
has been actively engaged in studies of the 
upper atmosphere using radio waves. The 
original approach, which began in the au- 
tumn of 1924, laid the foundation for the 
enormous proliferation of pulse radio, with 
its applications to radar and communica- 
tion, in addition to providing highly analyt- 
ical procedures for the study and predic- 
tion of radio communication pathways in 
their relation to solar activity. The estab- 
lishment of the Central Radio Propaga- 
tion Laboratory at the National Bureau of 
Standards for systematic ionosphere studies 
over our part of the globe relieved the De- 
partment in 1946 of its far-flung responsi- 
bilities for ionosphere operations. The de- 
cision was made to emphasize research 
activities, and hence small-scale operations, 
since research is invariably a personal ac- 
tivity of an individual or of two or three 
individuals with closely related fields of 
interest but different immediate problems. 

Radio "noise" signals which appeared to 
come from the plane of the galaxy were 
observed by Jansky, of the Bell Telephone 
Laboratories, in the early 1930's, and these 
observations were extended by Grote 
Reber in Illinois roughly ten years later. 
Radar interference from the sun during 
the war led to an active program in 
England and Australia for the study of 
radio stars and of radio noise from active 
spots on the sun, especially after the war. 



Activities along these lines in the United 
States have been somewhat less explora- 
tory and of narrower scope. It has become 
apparent, however, that the observational 
material of radio astronomy has direct 
bearing on other current interests within 
the Institution, and relates directly to our 
long series of studies on the upper atmos- 
sphere. About two years ago Mount Wil- 
son Observatory asked the Department, by 
reason of its long experience with similar 
electronic techniques, to develop a basis 
for assessment of the observational mate- 
rials and opportunities in radio astronomy 
in relation to the more traditional astro- 
nomical programs. A matter of particular 
interest for the Department has been the 
demonstrated relation of the scintillation 
of radio stars to the turbulence and mo- 
tions of ionized regions in the upper 
atmosphere. 

A vigorous start has been made during 
the past eighteen months toward several 
different types of specific studies in radio 
astronomy as a new direction in the evolu- 
tion of our upper-atmosphere studies. 

Radio astronomy owes its existence as a 
field of scientific endeavor to the fact that 
radio waves of wave lengths between 1 cm 
and 15 m which originate in celestial ob- 
jects can penetrate the earth's atmosphere 
and be detected from ground installations. 
Research on radio emissions at centimeter 
and decimeter wave lengths calls for differ- 
ent techniques and engineering methods 
from those required for research on emis- 
sions at meter wave lengths. For the re- 



100 



CARNEGIE INSTITUTION OF WASHINGTON 



ception of centimeter waves, radio tele- 
scopes are generally used, that is, antennas 
which are analogous to the reflecting tele- 
scopes used in the visual and photographic 
range of the spectrum. The large parabolic 
antenna (plate i) used for study of the 
hydrogen-line (21-cm) emission is an ex- 
ample of the radio telescope. At the longer 
wave lengths which are normally used for 
studies of radio waves from the sun or 
stars, however, a radio telescope having 
resolution comparable to that of the instru- 
ments used for centimeter waves would 
take on rather formidable proportions. To 
achieve the desired resolution, resort is had 
to a radio analogue of the interferometer 
technique used by Michelson and Pease 
at the Mount Wilson Observatory for in- 
creasing the resolving power of the 100- 
inch telescope. Michelson's optical inter- 
ferometer consists of two mirrors on a 
long beam across the aperture of the 100- 
inch reflector. The telescope is pointed 
toward a giant star whose diameter is to 
be measured, and the separation of the 
two mirrors is increased until the inter- 
ference fringes appearing at the eyepiece 
disappear. In the radio interferometer, an- 
tennas are substituted for Michelson's mir- 
rors, and electronic devices replace the 
100-inch telescope. A radio interferometer 
permits determination of the intensity, the 
location, and the angular diameter of a 
radio source. Such sources may be discrete 
galactic objects, extragalactic nebulae, the 
sun, or active regions on the sun. Accurate 
determination of the position of a radio 
source with an interferometer requires an- 
tennas oriented in different directions, usu- 
ally east-west and north-south, with sepa- 
rations of ten to several hundred wave 
lengths. The position measurements re- 
quire a precise knowledge of the position 
of the interference lobes as well as a high 
degree of stability in their direction. The 
lobe positions are determined from reg- 



ular calibrations, and the stability is 
achieved through careful instrumentation 
which eliminates or minimizes phase shifts 
arising in the amplifiers or interconnecting 
cables. 

Hydrogen-Line Emission from 
the Galaxy 

In September 1951, announcement was 
made of the experimental verification by 
Purcell and Ewen at Harvard of line emis- 
sion from atomic hydrogen at 1420.405 
megacycles. This faint emission from hy- 
drogen atoms, distributed with very low 
density between the stars, had been pre- 
dicted in 1944 by Van de Hulst in Hol- 
land. The significant feature of this emis- 
sion, which has been under observation in 
Holland and Australia almost since its 
first detection at Harvard, is that it is radi- 
ated at a fixed atomic frequency, and 
hence, by the Doppler effect, it is an excel- 
lent measure of the velocity of hydrogen 
gas clouds with respect to the earth. A 
great many interesting problems relating 
to the structure of our galaxy can be ap- 
proached with this new observational tool, 
and in fact an interpretation of the rela- 
tively limited observations to date has al- 
ready been made by Oort and others in 
Holland to show the probable existence of 
spiral arms in our own galaxy. 

Observations of this hydrogen line were 
begun at our Department in November 
1952, using a stationary parabola (Wurz- 
burg radar dish, on loan from the Na- 
tional Bureau of Standards). The com- 
plexities of interpretation due to the rela- 
tively brief time a given area of the sky 
(about two degrees in diameter) is under 
observation, and the necessity for sweep- 
ing the frequency through the expected 
Doppler range, made it clearly necessary 
to mount the receiving parabola on an 
equatorial axis. This was done during the 



Department of Terrestrial Magnetism 



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DEPARTMENT OF TERRESTRIAL MAGNETISM 



101 



winter, and observations began again at 
the end of April. The electronic proce- 
dures are complex, as the signal energy 
from the hydrogen in space is, for the 
most intense spots, only a little more than 
one per cent of the random noise in the 
radio receiving equipment. Measurement 
of these hydrogen signals therefore re- 
quires time averages over many seconds. 
The accumulation of reliable observations 
on this fascinating but faint light from 
the incredibly tenuous gas between the 
stars of our galaxy is necessarily a slow 
process. As the report year ends, all de- 
sign features have been worked out and 
tested for a multiple-channel apparatus de- 
signed to observe all Doppler frequencies 
continuously, giving separate and simul- 
taneous averaging on about 50 different 
frequency channels. Construction of this 
equipment will take several months, and 
meanwhile observations, anchored to the 
Dutch points on the galactic equator, are 
being made of gas clouds in several speci- 
fied directions. 

Active Radio Sources on the Sun 

A radio interferometer operating at 207 
mc/sec (1.45 m) for solar work has been 
nearly completed at the Derwood Experi- 
mental Laboratory in Maryland. It will be 
used for location of active regions on the 
sun with an accuracy of one minute of arc 
(1/30 of a solar diameter) and for study 
of their minute-to-minute fluctuations in 
position. The solar radio interferometer 
will have two pairs of antennas on an east- 
west line, spaced 50 and 170 wave lengths 
apart, respectively, and one north-south 
pair spaced at 50 wave lengths. An experi- 
mental version of the east-west spacing of 
50 wave lengths was first operating in 
November 1952 (see plate 2), and recently 
regular daily observations of the sun with 
this unit were started. The increased in- 



tensity of solar radio noise appears to origi- 
nate in relatively small disturbance centers 
associated with sunspots or other visible 
events on the solar disk. Some preliminary 
results have demonstrated the feasibility 
of identifying active radio sources with 
visible structures on the sun. It is expected 
that intensified collaboration in radio and 
optical observations will yield fruitful re- 
sults leading to a better understanding of 
the dynamic and physical properties of 
the sun and its atmosphere. 

Radio Star Scintillations 

The fluctuations of radio stars have been 
associated with irregularities in the earth's 
ionosphere by British and Australian inves- 
tigators. These scintillations were origi- 
nally thought to be actual variations in the 
intensity of the signals from the radio 
stars. Simultaneous measurements of radio 
star scintillations at stations separated by 
a few miles, however, gave results which 
demonstrated the existence of irregular re- 
fraction processes in our outer atmosphere. 
There is reason to believe that these fluctu- 
ations are caused by irregularities in the 
upper part of the F region of the iono- 
sphere which are not observable by ordi- 
nary methods of ionospheric sounding. 
Studies of these radio star scintillations 
promise to provide a new tool for investiga- 
tion of the electrical properties of our at- 
mosphere and for the observation of 
"winds" or traveling disturbances at 
heights which are otherwise inaccessible. 

The star scintillation experiment which 
is just getting under way will provide the 
first information from this continent. Pri- 
mary emphasis will be placed on the de- 
termination of diurnal and seasonal char- 
acteristics of the fluctuations at a frequency 
near 40 mc/sec. The results will eventu- 
ally be compared with those from other 
locations, such as Great Britain, for assess- 
ment of more global properties. 



102 



CARNEGIE INSTITUTION OF WASHINGTON 



Subsequently, the experiments may ex- 
pand to the operation of tripartite stations 
at spacings of a few miles for measure- 
ment of velocity and direction of the 
upper-atmospheric "winds." 

THE UPPER ATMOSPHERE 

H. W. Wells 

Traveling Disturbances 

The ionospheric program of 1952 added 
significantly to our knowledge of traveling 
disturbances in the E and F regions of the 
ionosphere. Still unanswered, however, is 
the fundamental question whether these 
phenomena are actual transport of ions as 
by winds, or the result of wave motions or 
the sweeping past of ionizing beams caus- 
ing transient irregularities in the distribu- 
tion of ionization. A significant fact which 
is emerging from our observations is the 
evidence that the F-region disturbances are 
moving predominantly from west to east 
at velocities of from 100 to 200 meters per 
second. (The velocity of sound in the same 
region is approximately 500 m/sec, and 
the rotational velocity of the earth at this 
latitude is approximately 350 m/sec, also 
west to east.) These results, however, are 
confined to daylight hours, since the local 
ionospheric irregularities, which require 
identification and precise timing at each 
station of our observing triangle, lose most 
of their identity at night. 

The size of the local ionospheric disturb- 
ances may be estimated from their veloc- 
ity and duration. Many of the larger 
"clouds" retain their identity for 30 to 40 
minutes. Probable dimensions are there- 
fore between 200 and 400 km. Smaller dis- 
turbances, having quasi periods of 10 
minutes or less, are often observed super- 
imposed on the larger ones. These may 
have dimensions of 50 to 100 km or less. 
From a meteorological point of view, the 
smaller disturbances often have the appear- 



ance of turbulence within the larger clouds. 
The observing program for 1953 pro- 
vides for improved instrumentation giving 
better time resolution. The three observ- 
ing stations will operate within a radius 
of 20 miles from the Derwood Laboratory, 
but a fourth station will be added as a 
check point. Efforts are being made to 
simplify the problem of data analysis by 
the operation of stations at selected fixed 
frequencies, rather than sweep frequencies. 
Some preliminary results from two sta- 
tions 15 miles apart give promise of signifi- 
cant improvement in ability to identify 
and time the traveling disturbances with 
precision. 

Pen-and-Ink Ionospheric Recorders 

The development of fixed-frequency 
ionospheric sounders, designed to produce 
pen-and-ink records of precise height and 
echo amplitude, was continued into the 
stage of practical field tests. One instru- 
ment was in intermittent operation at Der- 
wood for several months. Another instru- 
ment was operated simultaneously at the 
Poolesville (Maryland) site. The field 
tests revealed an inherent susceptibility to 
noise or other interfering signals which 
reduced the useful portions of records 
below our minimum requirements of per- 
formance. Accordingly, the radiofrequency 
components have been adapted to photo- 
graphic recording from cathode-ray indi- 
cators, and the modified instruments are 
being used in the program for investiga- 
tion of traveling ionospheric disturbances. 

Forward Scatter Experiment 

An experiment for determining the ef- 
fectiveness of forward scatter from the F 
region in supporting long-distance propa- 
gation of ultra-high-frequency signals has 
been pursued only intermittently because 
of pressure of other interests. The develop- 



DEPARTMENT OF TERRESTRIAL MAGNETISM IO o 

ment of a high-power pulse transmitter at been primarily the accomplishment of a 

43.5 mc was curtailed by delays in obtain- survey, except in limited regions; we have 

ing the required special license. Subse- been concerned with the development of 

quent field tests under conditions simulat- analytical procedures for obtaining and 

ing forward scatter from the E region evaluating information about the structure 

produced marginal signals except during of the outer crust of the earth. Over 2200 

periods of meteoric activity. At such times, records at different observing sites from 

the signals were heard distinctly in Florida, roughly 270 explosions, each using 1200 to 

but reports from Peru were negative. It is 3000 pounds or more of high explosive, 

planned to resume the experiment in the have been made in the course of our 

fall of 1953, using a simplified transmitting studies. About a third of these are in the 

antenna of high gain (corner reflector eastern United States, the rest in New 

type). Mexico, California, Minnesota, and Puget 

Some properties of meteor trails were Sound, 
studied, using an application of the radio These studies have made it quite clear 
interferometer technique. The meteor that the simplified textbook picture (de- 
trails were illuminated by a beamed con- duced some years ago from near-earth- 
tinuous-wave transmitter operating at quake studies) of the outer crust of the 
Cedar Rapids, Iowa, on a frequency near earth, just below the sedimentary rocks, as 
50 mc. The ionization produced by the a succession of granitic and basaltic layers 
rapidly moving head of the meteor simu- underlain by a mantle of ultrabasic rock is 
lated the moving-point source as studied hardly in accord with the complexities ac- 
by interferometer techniques in radio as- tually found in the field. Using individual 
tronomy. By use of a phase-sensitive de- instruments and arrays of instruments 
tector it was possible to measure a compo- spread over 1 km or more, at locations de- 
nent of velocity across the interferometer termined to within 0.1 km, and with the 
pattern. Similarly, the path length of the timing of the shot and the travel times 
meteor in the ionized medium may be of the waves accurate to within 0.02 second, 
measured by the number of interference we find real fluctuations in time and ampli- 
fringes produced. Estimates of meteoric tude which must be ascribed to a variety of 
velocities and path length were found to structures in the crust and not simply to 
be consistent with results obtained from the variations in rock structure within a 
other sources. few hundred feet of the instruments. 

Vigorous efforts have failed to find any 

THE EARTH'S CRUST indication of intermediate horizontal layers 

Seismic Studies °^ basaltic rocks, and in fact earthquake 

observations are clearly not suited to defin- 

H. E. Tatel and M. A. Tuve ing such layers as haye been postulated> 

Comprehensive examination of the large Nevertheless, strong "second returns" of 

body of observations made during the past energy appear at about two-thirds of the 

six years on the wave motion of the earth observing stations, in various locations at 

at distances of 1 to 1000 km from individ- 100 to 150 km from the shot. These have 

ual explosions has been emphasized dur- been tentatively identified as reflections 

ing this year. Additional field observations from a sharp transition between the upper 

are no doubt needed for the study of many crustal rocks (below the sediments), which 

obscure points, but our purpose has not have average wave velocities of 6.0 or 6.1 



I0 4 CARNEGIE INSTITUTION OF WASHINGTON 

km/sec, and the underlying ultrabasic sharply refracted) ray should give an addi- 

rocks of higher velocity (8.0 or 8.1 km/ tional set of data. Data showing the loca- 

sec) which are believed to comprise the tions of appearance and disappearance of 

outer parts of the mantle of the earth, these reflections make it possible to exclude 

Nowhere have velocities as low as 5.6 certain variations of velocity versus depth, 

km/sec (the old earthquake value for all For example, the velocities and crossover 

"granitic" rocks) been found, nor is there points may be used to calculate the depth 

any reliable evidence for intermediate ve- of crust and point of critical reflection on 

locities of 6.3, 6.7, or 7.3, which have been the basis of a simple hypothesis of no ve- 

traditionally assigned to the "intermediate locity change with depth. Critical reflec- 

basaltic layers." Instead, we consider that tion points at 63=1=4 and 86 ±6 km are 

the real fluctuations in our travel times predicted from the crossover points for the 

show that the 6.0 and 8.1 velocities are Maryland and Minnesota regions, respec- 

not specific values for specific types of tively. The observed points for first ap- 

rock, but are averages in each case for the pearance of strong reflections are about 85 

velocity of waves through many kilome- and 130 km, respectively. The discrepancy 

ters of mixed rocks. There is no evidence may be most easily explained by the effect 

that the 8.1 velocity for the mantle repre- of an increase in velocity with depth in the 

sents anything but an average over many crust. Thus we are led to conclude that 

kilometers, and it is entirely possible that the velocity of the crustal rock does in- 

structures occur in these mantle rocks as crease with depth, and certain limits may 

well as in the crustal ones above them. be set for the manner in which the veloc- 

The observations show that the velocity ity changes with depth. For example, 

of propagation in crustal rock must in- under Maryland the average velocity of 

crease with depth, from 6 to say 7 km/sec. the upper two-thirds of the crust could be 

This conclusion is based on additional in- 6 km/sec and that of the lower third 

formation derived from the observation of slightly greater than 7 km/sec. 
critical reflections. Without critical reflec- Furthermore, in the lower third of the 

tions, there are usually only three variables crust, the velocity need not be constant, 

which may be observed in a crustal seismic It may be constant at 7 km/sec or may 

study; namely, the upper crustal velocity, start at 6 and increase ever more rapidly 

the upper mantle velocity, and the distance with depth to 8 or just under 8 km/sec. 

from the explosion at which one velocity More data will be necessary to choose 

merges into the other (the crossover among the possible transitions in this 

point). From these data it is possible to lower zone of the crust, 
compute the depth at which the seismic In our search to establish the existence 

velocity changes from the crustal velocity of the critical reflection and to discover the 

(6 to 7 km/sec) to the upper mantle ve- qualitative nature of the crustal structure, 

locity (about 8 km/sec). Now there is we have chosen to observe at points along 

a large variety of possible velocity-versus- the earth's surface where we should most 

depth relations which will fit these data likely encounter the strong second arrivals 

equally well; and the usual seismic studies associated with total reflection (or refrac- 

afford no criterion which singles out one tion). At present we are making addi- 

such relation from the others. If, however, tional observations near the point of criti- 

conditions are such that a strong reflection cal reflection. Data of this type should 

may be observed, then this reflected (or give us more reliable information con- 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



105 



cerning the nature of the crustal transition. 
There is no indication in any of our meas- 
urements, at any depth, of a layer with 
lower velocity than that of the rocks above 
it, and we see no reason to think that such 
a layer might be useful in explaining any 
of our observations. 

Several features of seismic observations 
stood out as unexplained puzzles at the 
beginning of the year. One of these is the 
general phenomenon of reverberation: 
Wave energy from a distant shot arrives 
at an observing point; one might expect 
the wave to pass on and the observing site 
to regain its tranquility. It is a conspicuous 
feature of all seismic observations that this 
does not happen; after the "first arrival" 
of waves, by whatever path may be appro- 
priate to the position of the observing site, 
the ground continues in strong unrest, 
comparable to the disturbance when the 
wave front first reaches the instrument. 
Wave fronts may travel by several paths 
through the crust and the mantle, and may 
be of compressional or shear type, but they 
are usually separated by many seconds at 
the receiving site. The problem is to ac- 
count for the shaking of the ground which 
continues between these events. Theoreti- 
cal analyses of the travel of waves in a 
model homogeneous earth show no con- 
tinued vibrations. It is conceivable that 
if inhomogeneities and topographic fea- 
tures of the order of a wave length were 
introduced into these models, undulations 
like those recorded in a seismograph might 
result. Incidentally, reverberation has a 
disastrous effect on "signal-to-noise ratio," 
as a wave packet arriving later by a slower 
path cannot readily be observed on the 
background of large unrest which remains 
after the earlier wave arrivals. This phe- 
nomenon of reverberation is related to two 
or three other puzzling features, including 
that of partial coherence in wave patterns 
over many seconds at a set of receiving 



stations spread out over as much as 2 km. 
The motion of a given point on the surface 
is of course necessarily related to the mo- 
tion of adjacent points, but the apparent 
velocity of these coherent wave patterns 
traveling over the surface for many kilo- 
meters corresponds to the velocity of the 
deep-lying rocks (6.1 km/sec), and not to 
the velocity of the soil underlying the 
instruments (as low as 3 km/sec in some 
cases) . That is, the waves may have the true 
(group) velocity of secondary Rayleigh 
waves, but an apparent (phase) velocity of 
the originating wave. These observations 
give rise to questions as to the strength or 
even preponderance of local effects of ter- 
rain near the observing sites. Such effects 
might arise, for example, from conversion 
of one wave type to another at a surface. If 
local effects predominate, one must ques- 
tion the reliability of the detailed motion of 
the earth at any point on the surface as an 
indicator of the waves arriving in that gen- 
eral vicinity from the shot. This local sur- 
face motion may be very strongly affected 
by near-by topographic structures, and thus 
it may be nearly impossible to get a repre- 
sentative measure of the actual wave mo- 
tion in the heavier rocks below the surface 
by any instruments which can be placed 
upon the surface. 

Other questions concern the velocity 
transition from 7 to 8 km, here referred 
to as the "Mohorovicic discontinuity," fol- 
lowing old terminology. Is this in fact a 
discontinuity, giving rise to a reflected 
wave, or may it be a transition zone sev- 
eral kilometers thick, giving rise to a 
strong second arrival by focusing effects 
on refracted waves? What limits may our 
data set on the possible variation of veloc- 
ity with depth from the surface down to 
the Mohorovicic discontinuity? A fur- 
ther question concerns the degree of vol- 
ume inhomogeneity or structure in the 
crustal rocks, and the existence of struc- 



I0 6 CARNEGIE INSTITUTION OF WASHINGTON 

tures of varied rocks in the mantle region volume of the medium are converted near 

below the Mohorovicic discontinuity. As the receiver site to surface waves, which 

a part of the whole program, which is di- can spread out in only two dimensions in- 

rected toward the elucidation of continental stead of three, a basis is given for under- 

structures, their geological history, and the standing the continued ground motion 

way in which they differ from ocean basins, after the arrival of the first wave fronts, 

it is also appropriate to examine what other In this case the energy cannot be reflected 

types of measurement, for example gravity back into the volume, but dies away with 

variations, can give information on such time and distance much more slowly as 

questions about crustal rocks. it moves away in the surface layers. 

Several features stand out in the analy- This conception of the importance of 
sis of our large series of seismic shot rec- conversion near the receiving site, which is 
ords. One of these, as noted above, is the necessarily on the surface of the earth with 
reverberation or continued ground motion all its topographic irregularities, led us to 
which follows the arrival of any conspicu- undertake analytical experiments to ascer- 
ous group of waves; another is the tan- tain whether either the first arrival or the 
talizing degree of coherence or quasi peri- strong Mohorovicic reflection (both of 
odicity of the waves as they pass over a which for brief intervals are clear-cut corn- 
group of instruments spread over 2 km, as pressional wave impulses) is converted in 
shown by our many tests with 24 and even a cycle or two into Rayleigh wave motions 
48 simultaneous records using seismom- which continue as "reverberation." Theo- 
eters 150 to 300 feet apart (pi. 3). Coherent retical work of H. Lamb (1904), H. Na- 
wave groups were sought as reflections kano (1926), and E. R. Lapwood (1949) 
from the horizontal intermediate layers at indicates that conversion to Rayleigh and 
depths of 6 to 20 km which have so long more complex waves is expected when 
been postulated in the earthquake litera- compressional waves encounter strongly 
ture. The coherent wave patterns observed curved boundaries. Rayleigh waves give 
over a considerable area at the surface characteristic elliptical motion to the par- 
resemble the wave returns to be expected tides of an idealized surface. To examine 
from such layers at intermediate depths, this hypothesis, a special combination of 
but they are strongly dependent on shifts two strain seismometers and one vertical 
of the shot position as well as on shifts of seismometer was devised, such that Ray- 
the receiving array of seismometers, hence leigh waves impinging on the array from 
they do not correspond to returns from any direction in the surface give rise to 
buried horizontal boundaries. The strong zero net response, although the seismom- 
dependence of these coherent wave group- eter array retains full sensitivity to com- 
ings on receiving site, observed in Mary- pressional or other wave types. If the 
land, Minnesota, and Washington, sug- reverberation consists chiefly of Rayleigh 
gested to us that a possible phenomenon of waves from various directions in the sur- 
major importance in all seismic observa- face, this new seismometer array will give 
tions is the conversion of compressional a great enhancement of signal-to-noise ra- 
waves which impinge on a surface, es- tio in detecting the arrival of successive 
pecially an irregular surface, to surface new "phases," which are compressional or 
waves of various types, especially Rayleigh shear waves arriving by various ray paths, 
waves. If body waves arriving through the This could be of great practical importance 



Department of Terrestrial Magnetism 



Plate 3 




ARRAY 

TOP NORTH KEYS, MO. (NW) MARCH 6, 1951 A=47.7KM 

LOWER ETHEL, VA. (SW) MARCH 15,1951 A=48.4KM 

Multiple seismograms for studies of the earth's crust. The two records of explosions about 50 km 
distant show the ground motion during 2.4 seconds after the first observed arrival (9 seconds after 
the shot). Each set of 24 traces shows recordings of pairs of seismometers set 150 feet apart, ex- 
tending 2400 feet in the direction of the shot and 1200 feet perpendicular to the shot direction. The 
upper record was made 48 km northwest of the shot, and the lower 48 km southwest of the shot. The 
two sets of seismograms show the great differences in detail of two similar situations and illustrate 
the phenomenon of "reverberation." 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



107 



in geophysical prospecting. In addition, it 
was realized that observations at a depth 
of a wave length (about 2000 feet) or two 
in a mine or borehole should show very lit- 
tle reverberation if the latter phenomenon 
consists primarily in the trapping of energy 
in the form of waves which by their na- 
ture are tied to the surface. 

It is not always feasible to obtain ten or 
twenty successive large explosions in ad- 
vantageous locations. Deep mine observa- 
tions, which seem to call for explosions in 
the Great Lakes, have not yet been feasible. 
The strain seismometer array for analyti- 
cal tests seeking Rayleigh conversion waves 
was ready for observations in January 1953, 
but for several months thereafter the U. S. 
Navy was unable to carry out its normal 
program of test explosions in and near the 
Chesapeake Bay. When observations could 
be begun in May on relatively small ex- 
plosions, it was found that the ground mo- 
tion at several sites was clearly more com- 
plicated than a simple Rayleigh wave 
following the compressional phase. It is 
surprisingly difficult to locate sites on ex- 
posed rock surfaces which undergo appro- 
priate strain as the shot waves pass; the 
total ground motion, vertical and hori- 
zontal, seems almost arbitrarily related to 
the amount and direction of strain in the 
rock face. These experiments make it evi- 
dent that much of the surface of the earth 
is like rubble on a large scale, and no 
simple wave forms can be expected from 
instrument arrays on the surface, even if a 
simple wave impinges on such a surface 
from below. 

These experiments are actively continu- 
ing as the report year ends, and they ap- 
pear to demonstrate the very strong local 
influence of contour and topography, in- 
cluding buried topography, in the imme- 
diate vicinity of a seismometer receiving 
site. The strong conversion of body waves 
to surface waves thus appears to be a 



sound basis for understanding the local 
coherence of waves over a region several 
kilometers in extent; the propagation of 
phase patterns which have the appearance 
of a 6 km/sec velocity over surface sedi- 
ments where the velocity is known to be 
much lower; and the phenomenon of re- 
verberation, by trapping wave energy near 
the surface. Methods for signal-to-noise 
reduction which are based on idealized pic- 
tures assuming homogeneous media seem 
inevitably to be inapplicable to the rough 
surface of the real earth. 

In order to be sure that, in our efforts 
toward critical evaluation of seismic record- 
ings, simplified but not erroneous deduc- 
tions are made concerning the crust, we 
have made numerous instrumental com- 
parisons during recent years. It has been 
important in field work to be able to use 
filter discrimination against stray 60-cycle 
pick-up, for example, and the relative 
weakness of high-frequency components 
at distances of 50 to 300 km from a shot 
has seemed to justify elimination of high- 
frequency response. During the autumn 
of 1952 a series of tests were carried out 
using our standard electromagnetic instru- 
ments (velocity response) with frequency 
range about 3 to 30 cycles, comparing these 
with our older large seismometers (1 to 
30 cps) and with a high-frequency ve- 
locity instrument with photographic re- 
cording (3 to 300 cps). In addition, a dis- 
placement response instrument (capacity 
bridge; response 1/3 to 30 cps) was oper- 
ated at the same sites. All these instru- 
ments made practically identical records, 
and unequivocally the same interpretation 
would have been reached using any one 
of them. We therefore conclude that our 
surveys have not been biased by instru- 
mental response characteristics. On the 
basis of these tests, several sets of compact 
portable equipment, both two-position re- 
connaissance units and six-position seismic 



I0 8 CARNEGIE INSTITUTION OF WASHINGTON 

"strings" for linear arrays (1600 feet), were (stability). Thus, the findings of the past 

constructed and have been found very con- year put us in a better position ultimately to 

venient and reliable for field use. select rocks whose magnetizations can be 

used in tracing the history of the earth's 

Rock Magnetism magnetic field in geologic time. 

John W. Graham On the basis of our earlier observations, 

At the beginning of the report year, a we had offered ( Year Book No - 5°. '950- 
number of important questions remained '95 1 ) the suggestion that the direction of 
in the broad problem of interpreting rock ma g n etization of some rocks, under par- 
magnetism data. Whereas our studies on tlcular circumstances, could undergo a self- 
sediments favor the view that the earth's reversaL Observations reported during 
magnetic field has remained essentially J 95 2 h Y colleagues in the U. S. Geological 
constant in direction throughout geologic Surve y and m J a P an a PP«red to confirm 
time, the work of others on igneous rocks thls suggestion: Balsley and co-workers 
appears to suggest that there may have re P orted a correlation of high titanium con- 
been a number of reversals of the sense tent ln certain rocks wlth an inverse P olari - 
of the field. Both these interpretations are zatl0n > and Na g ata sported on a rock, 
subject to uncertainties because, first, there hl g h in tltamum > that squired an inverse 
is only partial understanding of the mech- moment when it was cooled from high 
anisms by which rocks become magnet- temperature m the earth's magnetic field, 
ized, and, second, the factors that control These observations, together with Neel's 
the stability of the magnetizations in time earller theoretical treatment of the prob- 
have not been adequately established. lem > suggested to us a group of field ob- 

,-. , .i • j- . . .. i iL servations which were expected to give 

Our work this year was directed at both ,. . f ° 

,u ..• i .i i u j- direct confirmation of the hypothesis that 

these questions, primarily through studies ,e 

on igneous rocks. Out of this work has Certain 1 § neous ™ cks ™ th inverse ma §' 

come the appreciation that magnetized negations are to be explained, not on the 

minerals may develop in rocks at more basis of a °nce-reversed earth's field, but 

than one time, for example by oxidation, rather on the basis o£ the P resen ce in the 

and that the later-formed species may de- rock of two distinct ferromagnetic min- 

rive their magnetizations from the pre- eral s P ecies havin S different Curie points, 

viously magnetized material, rather than and an interaction of their magnetic fields, 

directly from the earth's magnetic field. Jt was suggested that there might be 

We have recognized that impurities con- found, on the margins of an igneous intru- 

tained in magnetite at high temperature sive characterized by an inverse magnetiza- 

may have an important influence on mag- tion, a zone of rapidly cooled rock having 

netic properties at lower temperatures as normal polarizations, the thought being 

they are rejected from the magnetite struc- that suitable rapid cooling would suppress 

ture upon cooling, by exsolution processes, the development of the two phases necessary 

The primary effect of eliminating impuri- for the self-reversal. This suggestion was 

ties is in controlling the grain size of the put to test during six weeks of field work 

magnetite. From magnetization experi- on a group of small and large Pre-Cam- 

ments we now realize that grain size is brian diabase dikes in Michigan known to 

important in controlling the ease with have inverse magnetizations. Approxi- 

which the magnetization can be altered mately 250 selected samples were measured 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



109 



in the field, and provided a basis for fur- 
ther study during the winter. Contrary to 
expectation, samples from even the mar- 
ginal fraction of an inch of a dike only a 
foot and a half wide had the same sense of 
magnetization as samples from the interior 
of a related dike 150 feet wide. Since 
abundant evidence is available that rapid 
cooling did in fact take place on the mar- 
gins, field confirmation of the self-reversal 
mechanism was not obtained. 

The laboratory work that followed made 
apparent the reason for this result. By a 
combination mainly of X-ray diffraction 
measurements (made at the Geophysical 
Laboratory) and heating experiments it 
was demonstrated that the fraction re- 
moved from the rock by simple magnetic 
separation consists of a mixture of two 
distinct ferromagnetic species — magnetite 
(Fe 3 4 ) and maghemite (YFe 2 3 ) — inti- 
mately intermingled with each other and 
with "nonmagnetic" ilmenite (FeTi0 3 ). 
Maghemite is not a primary constituent of 
igneous rocks, but is developed at rela- 
tively low temperatures by the oxidation of 
magnetite. On being heated to 400-600° C, 
it is converted to nonmagnetic hematite. 
Hence, high-temperature experiments to 
determine the original magnetic behavior 
of these rocks cannot be made, because 
part of the magnetic material of the natu- 
ral sample is destroyed in the experiment. 

During the past few years, solid-state 
physicists have made great progress toward 
an understanding of the magnetic prop- 
erties of tiny particles. Their outlook has 
been used to good advantage in some of 
the problems of rock magnetism. For ex- 
ample, by means of magnetization experi- 
ments on the Michigan dike rocks, it has 
been possible to demonstrate that the ferro- 
magnetic ingredient behaves magnetically 
like a mixture of small and large particles. 
The small particles, whose state of mag- 
netization is more difficult to change (high 



coercive force), are responsible for pro- 
ducing the magnetization observed in the 
natural samples. The larger particles in 
the natural samples are in a "demagnet- 
ized" state, but may be easily remagnet- 
ized. The combination of these two types 
of particle in the rocks produces an inter- 
esting magnetic behavior. If a sample is 
subjected momentarily to a moderately 
strong magnetic field (100 oersteds), its 
state of magnetization is greatly changed. 
If, however, this remagnetized sample is 
now placed in an alternating magnetic 
field of 100 oersteds peak value that is 
allowed to decay slowly, the original state 
of magnetization of the sample is restored. 
Such behavior appears contrary to the 
usual experience that a decaying alternating 
magnetic field will demagnetize a sample, 
but it may be easily interpreted in the light 
of the recently acquired understanding of 
the differences of behavior of small and 
large particles. Microscopic observation of 
this magnetic material indicates that the 
magnetic properties are the consequence of 
the macroscopic grains' being very finely 
subdivided by the development of isolated 
bodies of ilmenite which could not be re- 
tained in solid solution within the mag- 
netite crystal structure at low temperature. 
These field and laboratory observations 
have been synthesized in an internally con- 
sistent hypothesis which explains how these 
rocks could acquire their magnetizations 
in an original magnetic field having a 
sense opposed to that shown by the sam- 
ples today. The magnetization mechanism 
of these rocks is visualized as follows: 
Magnetite, containing an abundance of 
titanium in solid solution at high tempera- 
ture, is minutely subdivided at lower tem- 
peratures as excess titanium is rejected in 
the mineral ilmenite; this complex type 
of body becomes magnetized to high in- 
tensity in the same sense as the applied 
field as it cools below the Curie point of 



no 



CARNEGIE INSTITUTION OF WASHINGTON 



magnetite; at still lower temperatures, oxi- 
dizing reactions become important, and 
maghemite is produced at the expense of 
the more reactive small particles of mag- 
netite. The net sense of magnetization of 
these secondary maghemite particles is op- 
posite to the sense of magnetization of the 
primary magnetite and hence also oppo- 
site to the sense of the magnetic field pres- 
ent at the time the melt initially cooled. 
With the passage of time, the larger, un- 
altered particles of magnetite become de- 
magnetized, and the sense of magnetiza- 
tion of the sample becomes dominated by 
the moments of the smaller particles — the 
reverse of the original applied field. 

Inasmuch as this magnetization process 
requires many steps over a period of time, 
it is possible that in nature the normal 
sequence may be interrupted and later re- 
sumed. In this way it would be possible 
for the magnetic moment of sediments to 
reverse at some time subsequent to deposi- 
tion. Such appears to have been the case 
in some of the sediments within the Ap- 
palachian geosyncline, which were sub- 
jected to elevated temperatures and deep 
burial after their deposition. 

Observations of the directional magnetic 
susceptibility of samples from the Michi- 
gan diabase dikes have indicated that 
turbulent flow or movement below the 
Curie point is not the cause of the scattered 
directions of magnetization observed in 
some exposures. Tentatively, the scatter is 
attributed to local variations produced in 
the chemical composition of the diabase by 
thermal gradients at the time the dike was 
injected, but the manner in which the scat- 
ter is produced is not fully understood. 

Other studies of the anisotropy of mag- 
netic susceptibility made during the year 
indicate that this property is related pri- 
marily to textures produced in rocks at 
the time of their formation or most recent 
deformation. The subject warrants de- 



tailed attention by geologists who are in- 
terested in the textural and structural evo- 
lution of rocks. 

Isotope Dating of Ancient Igneous 
Intrusives 

L. T. Aldrich, G. L. Davis, L. O. Nicolaysen, 
and G. R. Tilton 

The co-operative program of staff mem- 
bers of the Department of Terrestrial 
Magnetism and the Geophysical Labora- 
tory designed to ascertain age relations 
between the igneous intrusives of Pre- 
Cambrian time has been continued this 
year. This program is a part of a general 
focusing of attention here on questions 
relating to the characterization of con- 
tinental structures and their probable evo- 
lution, with particular reference to the 
long stretches of time before the Cambrian 
period. 

Until recently, methods of absolute age 
determination have been limited in appli- 
cation to ores of radioactive elements, prin- 
cipally uranium and thorium, for which 
gravimetric determination of the parent 
and daughter elements is possible. During 
the past few years an accurate method of 
determining very minute quantities of ele- 
ments having more than one stable isotope 
has been developed, widening the scope of 
age measurements to common rock-form- 
ing minerals and to radioactive elements 
other than uranium and thorium, such as 
potassium and rubidium. The increased 
sensitivity of this isotope dilution method 
makes possible for the first time age deter- 
minations by several radioactive decay sys- 
tems on a single igneous rock mass, thus 
providing an opportunity to compare the 
reliability of the results obtained by the 
different systems. When the reliability of a 
method has been established, a large vari- 
ety of geochemical and geophysical proc- 
esses may be studied, including diffusion, 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



III 



rock alteration, and mineral formation. 
The availability of a source of dated min- 
erals makes possible a study of natural 
nuclear physical rate processes such as 
branching ratios, neutron flux in rocks, and 
natural fission. At the beginning of the 
present year's work, the rubidium-stron- 
tium ages of five lepidolites and the ura- 
nium-lead ages of the zircon and sphene 
of the Essonville granite had been deter- 
mined. 

The activities of this year started with an 
extensive field trip to the mapped Pre- 
Cambrian areas of southern, southwestern, 
and western United States. A party of 
geologists, chemists, and physicists from 
our two laboratories collected granites and 
pegmatitic minerals for laboratory investi- 
gation from selected localities in Texas, 
New Mexico, Arizona, California, Mon- 
tana, Wyoming, and Colorado. Wher- 
ever possible, geologists working in the 
particular areas were consulted. Their 
support and assistance proved to be in- 
valuable in obtaining representative ma- 
terials. 

Specimens were collected from sixteen 
type localities of significant granite masses, 
and lepidolites were found in five peg- 
matites, four of which were seemingly as- 
sociated with granite bodies. Accompany- 
ing minerals such as feldspar, biotites, mus- 
covite, amblygonite, beryl, and tourmaline 
were also collected at the pegmatite locali- 
ties for laboratory evaluation as to their 
suitability either for age determination or 
for measurement of isotope ratios. It is a 
pleasure to acknowledge the assistance and 
advice of the many people who helped 
make the sample collection a success. They 
include Dr. C. A. Anderson, Medora Krie- 
ger, and Dr. T. S. Lovering, of the U. S. 
Geological Survey; Dr. R. Jahns, Cali- 
fornia Institute of Technology ; Dr. Arthur 
Montgomery, Lafayette College; and offi- 



cials of Grand Canyon, Yosemite, and 
Yellowstone National Parks. 

Thin sections of all rock samples were 
prepared for petrographic examination, 
and the granites were crushed for mineral 
separation. Combinations of magnetic and 
density separations were employed to yield 
pure samples of the constituent minerals. 
In some unfavorable cases 50 pounds of 
rock yielded but 100 mg of zircon, barely 
enough for preliminary analysis. Mineral 
fractions of zircon, sphene, and biotite 
were extracted from granite collected at 
Cape Town, Union of South Africa, and 
from a heavy mineral concentrate from a 
granite in Southern Rhodesia. The latter 
was obtained through the co-operation of 
Dr. A. M. MacGregor, of the Rhodesian 
Geological Survey. 

Determination of Thorium by Isotope 
Dilution 

Considerable attention has been given 
by authors of various papers in recent years 
to quantitative chemical measurements 
made by the method of isotope dilution. 
The availability of stable isotopes from the 
Atomic Energy Commission has made the 
method practicable. An example of the 
method, the determination of thorium, is 
given here, since it demonstrates both the 
method and a type of physical measure- 
ment which can well be made on suitable 
rocks. 

Thorium in thorium-bearing minerals 
has but one isotope, Th 232 , as shown in 
figure \a. To determine thorium by the 
method of isotope dilution, another iso- 
tope of thorium in milligram quantities 
must be found. Th 230 , not yet available 
from the AEC, is a daughter of U 238 , of 
sufficiently long half life to be present in 
nearly pure form in originally thorium- 
free uranium minerals. About 1 mg of 
such thorium was extracted from an old 
pitchblende and made into the carrier 



112 



CARNEGIE INSTITUTION OF WASHINGTON 



solution for determining thorium in min- 
erals. The isotopic composition of the car- 
rier material is shown in figure \b, from 
which it is seen that the ratio Trr 30 /Th 
is about 4. The carrier solution is cali 



232 



thorium in a rock, a known volume of car- 
rier solution is equilibrated with a solution 
containing all the thorium of the speci- 
men. A fraction of the thorium sufficient 
for mass spectrometric analysis is then ex- 




230 232 
NORMAL THORIUM 



Th 



230 
230 



232 230 232 

CARRIER 3.496 y NORMAL Th 

+ 
0.100 ml CARRIER 
SOLUTION 



230 232 

0.100 ml CARRIER 
SOLUTION 

+ 

0.0946 g CAPE ZIRCON 



Fig. 1. Mass spectra for the determination of very small amounts of thorium in mineral sam- 
ples by isotope dilution, (a) Thorium alone (no Th 230 ). (b) Mass spectrum of Th 230 carrier, 
Th 230 /Th 232 = 3.9. (c) Mass spectrum for calibration of carrier solution, 3.5 [ig normal thorium 
+ 0.1 ml carrier solution. Th 230 /Th 232 = o.92, hence Th 230 content of carrier solution is 4.2 \xg/ 
0.1 ml. (d) Mass spectrum of thorium from mixture of 0.1 ml carrier solution and 0.09 gm zircon 
from the Cape granite. Th 230 /Th 232 r=o.25, and Th 232 content of zircon = 15.7 (jg/0.0946 gm zircon. 



brated from this ratio and from that of a 
mixture of a known volume of the carrier 
solution to a known mass of Th 232 . The 
isotope distribution of the mixture is 
shown in figure ic. The data for the 
calibration of the carrier solution are now 
complete, and as many minerals may be 
analyzed as necessary. To determine the 



tracted and analyzed, and another isotope 
distribution is obtained (fig. id), from 
which the thorium content of the rock or 
mineral may be calculated. The method 
is applicable to all elements which have 
two stable or long-lived isotopes, and is 
only slightly more complex when the ele- 
ment to be analyzed has several isotopes. 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



113 



The application of the method to the 
determination of Th 230 and U 238 in suit- 
able uranium minerals will provide the 
data required for calculating the ratio of 
the decay constants of these two isotopes. 
This extension of the method to the meas- 
urement of nuclear constants promises to 
be fruitful. 

Elements which have been determined 
by the method of isotope dilution at our 
laboratory now include uranium, thorium, 
lead, strontium, rubidium, and calcium. 

Rubidium-Strontium Age 
Determinations 

The rubidium-strontium measurements 
have been extended to include some 25 
lithium micas, obtained from pegmatites 
located in Pre-Cambrian areas of South 
Africa and North America. Table 1 gives 
the measurements on South African peg- 
matites, and table 2 those for North Amer- 
ica. The absolute ages are determined 
from a decay constant for Rb 87 of 1.13X 
io -11 yr _1 , the average of two recent deter- 
minations by absolute beta counting. 

The ages (in millions of years) presented 
in table 1 confirm last year's findings 
on the existence of minerals whose ages, 
as measured by the rubidium-strontium 
method, are greater than 3000 million 
years. In addition, the ages of specimens 
collected from different pegmatites in a 
geologically homogeneous area agree with- 
in 10 per cent. In one instance, however, 
the disagreement between these measure- 
ments and published syntheses of African 
Pre-Cambrian tectonics is so striking that 
the need for reconsidering this problem is 
indicated. 

The results in table 2 show for the first 
time the existence of Pre-Cambrian pegma- 
tites in the United States as ancient as any 
in North America. The three pegmatites 
with ages of about 3500 million years are 



located roughly between the 2000-million- 
year-old pegmatites of the Black Hills, re- 
ported last year, and the 2700-million-year- 
old pegmatite at Bagdad, Arizona. The 
existence of very ancient minerals in the 
United States as far south as New Mexico 

TABLE 1 

Indicated age of South African pegmatites 

Age 
Location (million 

years) 

Popes Claim, S. Rhodesia 374° 

Letaba, Transvaal 3850 

Hombolo, Tanganyika 3 2 5° 

M'bale (1), Uganda 2460 

M'bale (2), Uganda 2370 

Lunya, Uganda 2 34° 

Kinderzitt, Namaqualand 1210 

Jakkalswater, Namaqualand 1100 

Muika (1), Belgian Congo 1220 

Muika (2), Belgian Congo 1210 

Karibib-Usakos II, SW. Africa 600 

Sahatany, Madagascar 690 

Alto Ligonha, Mozambique 570 

Dogon Daji, Nigeria 625 

TABLE 2 

Indicated age of North American pegmatites 

Age 
Location (million 

years) 

Bagdad, Arizona 2660 ±260 

Bonneville, Wyoming 357° — 3 00 

Dixon, New Mexico 3450 + 400 

Ohio City, Colorado 344° — 3 00 

will certainly contribute to theories of con- 
tinent formation. These measurements are 
also a part of the study of the correlation 
of ages indicated by different radioactive 
decay systems, which has the broad objec- 
tive of determining the reliability of age 
measurements by isotope ratios. 

Large variation in the isotopic abun- 
dances of the isotopes of strontium thought 
to be stable was reported last year. An at- 



ii 4 



CARNEGIE INSTITUTION OF WASHINGTON 



tempt was made this year to see whether 
this variation could be due to radioac- 
tive decay of zirconium or uranium con- 
tained in the mineral zircon. The absolute 
amount of strontium in the blank run in 
parallel with the zircon was 2.5 ± 0.5 micro- 
grams. That found in one gram of zircon 
was within 20 per cent of this amount. 
This can be considered good agreement be- 
tween two blank runs. It is therefore con- 
cluded that the radioactive decay of zir- 
conium or uranium in the amounts present 
in the mineral biotite could not contribute 
in any way to the variation of the ratio 
Sr 86 /Sr 88 found in biotite. It is of interest 
to note that the strontium determination in 
zircon was made using Sr 87 from lepidolite 
as carrier material. The purity of this iso- 
tope in the strontium in lepidolite is so 
high (99 per cent) that it is ideal for the 
determination of small amounts of com- 
mon strontium. 

Lead Age Program 

Thorium-lead age determinations on the 
mineral constituents of granites which are 
the first to include isotopic analysis of the 
lead have now been made. New uranium- 
lead ages have been obtained for those min- 
erals which had not been analyzed previ- 
ously. The lead analyses are the collabora- 
tive work of Dr. Claire C. Patterson, of 
the California Institute of Technology. 
Dr. M. G. Inghram, of Argonne National 
Laboratories, generously provided mass 
spectrometric facilities for the measure- 
ments made during the first half of the 
year. Granites from three localities have 
been studied during the past year: Esson- 
ville, Ontario (thorium ages) ; Uncom- 
pahgre, Colorado (uranium and thorium 
ages) ; and Cape Town, Union of South 
Africa (uranium and thorium ages). The 
Uncompahgre work is part of a detailed 
study of the distribution of lead, uranium, 



and thorium in the various mineral constit- 
uents of the granite, and of the isotopic 
composition of the leads, which will sup- 
plement a similar study on the Essonville 
granite already completed. The Cape gran- 
ite measurements are part of the study of 
thorium ages. 

The determinations are summarized in 
table 3. The ages given have an analytical 

TABLE 3 
Lead ages of granitic minerals 



Sample 



Age (million years) 



U 238 /Pt> 206 Pb 207 /Pb 206 Th 232 /Pb 208 



Essonville 
granite: 
Zircon .... 1030 1060 415 

Sphene.... 920±80 1060±200 202 

Uncompahgre 
granite: 
Apatite.... 1050 1810±160 200 

Biotite 3200 1700 1180 

Cape granite: 

Zircon 347 550 278 

accuracy of about 5 per cent unless other- 
wise indicated. The Cape zircon ages are 
based on preliminary data and are ac- 
curate to about ±10 per cent. 

Thorium Ages 

The striking feature of the thorium-lead 
ages is the fact that they are all much 
lower than the uranium-lead and lead-lead 
ages of the same minerals. This discrep- 
ancy has been found by other workers for 
a number of the uranium-thorium ores. In 
particular, five of the six monazite age de- 
terminations reported in the literature re- 
semble the data of table 3 in having low 
thorium-lead ages as compared with the 
uranium-lead ages. No adequate explana- 
tion has been offered for these observa- 
tions. Since it now appears that many 
granitic minerals can be expected to yield 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



115 



low thorium-lead ages, it is probable that 
the goal of future thorium work will be 
more to determine the cause of the dis- 
crepancy than to measure ages by this 
method. Some progress has been made 
with the problem during the past year, 
although the data are too few to permit 
generalization. 

The comparison between the Essonville 
and Cape zircons is noteworthy because 
X-ray examinations showed that the crys- 
tal structure of the Essonville zircon is 
badly shattered by radiation damage (met- 
amict), whereas that of the Cape zircon 
is nearly intact owing to its younger age 
and lower radioelement concentration. 
Since zircon is one of the most stable min- 
erals known, the Cape zircon represents 
one of the most favorable subjects for 
thorium-lead age measurements on a rock 
mineral. It is seen that the thorium-lead 
and uranium-lead ages agree much more 
closely for the Cape than for the Esson- 
ville zircon, even allowing for the fact that 
the Cape lead data are still of a prelim- 
inary nature. This agreement indicates 
that thorium age discrepancies in zircons 
may be a function of the interrelated quan- 
tities, the radioelement concentration, and 
the extent of crystal damage. 

An interesting result has been obtained 
by leaching the Essonville sphene with 
cold 6N hydrochloric acid and analyzing 
the solution. The solution was found to 
contain 20 per cent of the sample's ura- 
nium, 40 per cent of the thorium, and 70 
per cent of the lead. Moreover, the acid 
removed 65 per cent of the radiogenic 
Pb 208 , but only 25 per cent of the radio- 
genic Pb 206 . Thus for this mineral the 
lead generated by thorium is more sus- 
ceptible to removal than that generated by 
uranium. These observations would indi- 
cate that loss of Pb 208 rather than addition 
of thorium is the cause of the low thorium- 



lead age for the mineral. It is possible to 
lose Pb 208 without a proportionate loss of 
Pb 206 if there is an inhomogeneous distri- 
bution of uranium and thorium in the 
crystals. 

In the case of the Essonville zircon it 
has been found that a hot aqua regia leach 
will reduce the alpha activity of the min- 
eral by 35 per cent. This leach solution 
will be studied in the same manner as the 
sphene leach solution, in an effort to obtain 
further information on the problem of low 
thorium-lead ages. 

Uranium-Lead Ages 

The uranium-lead age of the Cape zir- 
con is less than the lead-lead age by an 
amount that is far outside the limits of 
analytical error. It is believed that the 
lead-lead age is the more nearly correct 
and that the uranium-lead age is low. The 
Essonville zircon occurred in the rock as 
large crystals several millimeters in di- 
ameter, whereas the Cape zircon occurred 
as small crystals but a few hundredths to a 
tenth of a millimeter in diameter. The 
hypothesis now favored is that the smaller 
size of the Cape zircon crystals permitted 
lead loss while the larger size of the Esson- 
ville crystals prevented it. We have no 
data for the diffusion rate of lead in zir- 
con, but data exist for the diffusion of lead 
in a perthite feldspar which indicate that 
it could diffuse in the mineral over dis- 
tances of the order of 0.1 mm in one bil- 
lion years at 300° C under the influence 
of a concentration gradient. 

The Cape granite contains minerals 
suitable for a rubidium-strontium age de- 
termination, and such a study is planned 
for the coming months. 

The Uncompahgre measurements seem 
only to show that the granite is older than 
one billion years. It is not possible to state 
at this time which of the age measurements 



n6 



CARNEGIE INSTITUTION OF WASHINGTON 



is likely to be the more accurate. A rubid- 
ium-strontium age measurement on the 
biotite will be made in the near future. 



Transfer of Lead in the Essonville Granite 

Further work on the Essonville granite 
has given evidence of a transfer of lead 
(and possibly uranium and thorium) with- 
in the minerals of the rock. The perthite 
present in the rock contains so much lead 
as compared with uranium and thorium 
that the isotopic composition of the lead 
could not have been affected by radioactive 
decay within the mineral during the bil- 
lion years the granite has existed, and 
should thus represent the lead present 
when the rock was formed. When one 
compares this measured isotopic composi- 
tion with that calculated from the known 
age and from uranium, thorium, and lead 
data for the rock today, it is found that the 
calculated ratios of Pb 206 , Pb 207 , and Pb 208 
to Pb 204 are substantially lower (see table 
4) . This indicates either addition of radio- 
genic lead to the feldspar or else a frac- 
tionation of lead from uranium and tho- 
rium in the rock as a whole. 

In view of this information, a large 
perthite crystal from a pegmatite in the 
Essonville area was analyzed for the iso- 
topic composition of its lead. Diffusion 
processes should have had much less effect 
here, since the crystal was several centi- 
meters in length, in contrast with the crys- 
tals of the mineral in the granite, which 
were but a few millimeters in length. The 
pegmatite lead agrees very well with that 
calculated from the total granite. It is 
accordingly believed that there has been 
no measurable fractionation of uranium, 
thorium, and lead in the rock as a whole 



and that there has been addition of radio- 
genic lead to the feldspar since it was 
formed. It is possible to leach highly radio- 
genic lead (i.e., lead with high ratios of 
Pb 206 , Pb 207 , and Pb 208 to Pb 204 ) from the 
sphene of the granite with cold 6N hydro- 
chloric acid. Such a process could serve as 
the source of the lead which has been 
added to the perthite. 

If such transfers of atoms between the 
various minerals of granites prove to be 
the general case, the interpretation of age 
measurements based on these minerals will 

TABLE 4 
Isotopic composition of Essonville leads 

Sample 206/204 207/204 208/204 

Perthite from granite 

(observed) 18.4 15.6 39 

Granite composite (cal- 
culated) 16.4 15.3 32 

Perthite from pegma- 
tite (observed) 16.7 15.0 35 

be greatly complicated. The studies of the 
coming year should give an indication of 
how important this factor will be. 

The measurements made this year indi- 
cate several things about the general prob- 
lem of age determinations. The need for 
cross correlation seems more important as 
we accumulate data from one decay system 
or another without comparison. The lead 
measurements already indicate the diffi- 
culty of determining unambiguously the 
age of a granite from the ages found for 
its mineral constituents. Determination of 
the age by the rubidium-strontium method 
may remove some of the ambiguity or in- 
crease it. In any case, the granites already 
on hand will provide the answer we need. 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



117 



THEORETICAL AND STATISTICAL GEOPHYSICS 



Statistical Study of Seismic Waves 
E. H. Vestine and S. E. Forbush 

The seismic records of explosions pro- 
vide geophysical time series which often 
exhibit an unfavorable signal-to-noise ratio. 
This sometimes happens for a compres- 
sional wave reflection return from the 
Mohorovicic layer at sites in the range 100 
to 200 km from the shot point. When this 
desired signal is weak, it may be lost in 
the general background noise, and may 
escape visual identification and timing in 
the record. The question then arises 
whether or not the desired signal can be 
identified after the systematic noise is fil- 
tered out by statistical methods. Similar 
problems concerning a specific wave re- 
turn or "phase" buried in the background 
from waves arriving earlier comprise much 
of the subject matter of seismic studies. 
This general question in relation to geo- 
physical prospecting was pointed out to us 
by P. M. Hurley and his colleagues at the 
Massachusetts Institute of Technology. 

Statistical methods based on Wiener's 
theory of stationary time series form a 
convenient starting point in this type of 
problem. By this means the record can be 
analyzed into self-correlated (autocorre- 
lated) time series and a random time 
series. The wanted signal, supposed to be 
of spiked form, can then be sought in the 
latter time series by sampling techniques 
applied to various intervals of record, us- 
ing suitable significance tests. 

These ideas were applied to three of 
the velocity seismometer records obtained 
by Tatel and colleagues from explosions 
in Minnesota and in the Appalachian re- 
gion. The particular records chosen were 
ones for which Mohorovicic reflections 
were clearly indicated by inspection of rec- 
ords from other stations closer to the shot 
point. In the records examined statistically, 



a Mohorovicic reflection which escaped 
visual detection was tentatively identified 
as probable in one record of the three 
examined. It was found that the autocor- 
relation in the first 4 seconds of record was 
the same or stationary, so that the auto- 
correlated signal could be removed by pre- 
diction technique. 

It has been tentatively concluded that 
the particular techniques used do not facili- 
tate the identification of a wanted spike 
signal in the noise unless the signal is large 
enough to have been suspected on visual 
examination of the record. Although based 
on an analysis of only three records, this 
result is not surprising and is entirely 
reasonable. It is possible, however, that 
cross-correlation techniques, suggested by 
P. M. Hurley and his co-workers, involv- 
ing a pair of suitably spaced recording sta- 
tions, might have afforded some improve- 
ment, especially for stations much closer to 
the shot point. 

In the case of a large blast in Tennessee, 
the autocorrelation of the vertical velocity 
component 1220 km from the blast showed 
three remarkably stationary levels cor- 
responding to the compressional, shear, 
and Rayleigh wave phases, in the fre- 
quency range of 3 to 30 cycles per second. 
Rigorous statistical tests of the vertical and 
horizontal seismometer records, however, 
failed to show any persistent wave or ellip- 
tical surface motion, corresponding to the 
so-called Rayleigh wave phase, at these fre- 
quencies. At 10 km from the Tennessee 
blast, the autocorrelation was variable, in- 
terval by interval in time, and thus unlike 
that found at distances of about 200 to 
1200 km. 

An unsuccessful attempt was made to 
identify the autocorrelated signal with sur- 
face waves generated at the earth's sur- 
face by reflected compressional waves, in 



n8 



CARNEGIE INSTITUTION OF WASHINGTON 



the manner suggested by H. Nakano and change in shape of the earth which might 
E. R. Lapwood. It was concluded that the ensue and in turn give rise to a possible 
available experimental data were of in- observed V 2 2 term in gravity, 
adequate quality for this purpose, but suit- Several members of the Department 
able analytical tests were developed which have been carrying on studies of the pos- 
should facilitate further examination of sibility that toroidal magnetic fields due to 
this question when satisfactory data on the electric currents generated at the juncture 
space gradients of elastic displacements be- of mantle and core (thermoelectric cur- 
come available. rents, for example) may in turn provide 

The mechanics of wave propagation of Hall currents required to generate a sub- 
the earth's crust is not well understood, stantial part of the main dipole and other 
It seems likely from the studies already components of the earth's observed mag- 
made that statistical and analytical methods netic field. Preliminary calculations are 
based on modern signal-to-noise ratio sufficiently encouraging to show that this 
techniques will be of material assistance in suggestion may merit serious consideration, 
clarifying the nature of the wave propaga- This is because the field of a small dipole 
tion involved. It may then be possible to inside the core in the presence of suitable 
improve instrument design so that wanted toroidal electric currents will yield Hall 
signals, when they occur, will be given currents effectively amplifying the dipole 
greater relative prominence in the record, field. The Hall coefficient for the base of 

the mantle is of course unknown, but no 

Fluid Motions in the Earth's Core reason has yet been found for supposing 

E. H. Vestine [t t0 be negligible. 



At the invitation of the American Geo- 
physical Union, a short study and discus- 
sion of problems of the earth's central core 
was undertaken. The evidence from the 
fluctuating westward and northward plane- 
tary motions of the geomagnetic field dis- 
cussed in last year's report in relation to 
fluctuations in the earth's rate of rotation 
was reviewed. These motions of the geo- 
magnetic field as a whole, noted at the 
earth's surface, are expected to describe 
corresponding motions in the surface re- 
gion of the core. In the same way it should 
be possible to determine from more local- 
ized features of the changing geomagnetic 
field some of the grosser motions occur- 
ring locally in the surface region of the 
core. A preliminary study suggests the 
possible presence of two rising and two 
falling centers of fluid motion near the 
equatorial plane of the core. An attempt is 
under way to check this by calculating the 



Toroidal Magnetic Fields in the 
Atmosphere 

E. H. Vestine 

A further point noted was that it may 
be possible to check the generation of 
toroidal magnetic fields on a geophysical 
scale by means of rocket-borne magnetom- 
eters in the upper atmosphere. In the 
highly conducting auroral regions, varia- 
tions in zonal wind velocity with height 
are likely to generate large toroidal mag- 
netic fields difficult to detect at the earth's 
surface. Such fields may afford a terres- 
trial explanation for effects on the latitude 
distribution of cosmic rays, for part of the 
variation with longitude in cosmic-ray in- 
creases during large solar flares, and for 
the existence and azimuth of homogeneous 
auroral arcs. In any event, the conclusion 
that toroidal magnetic fields exist in the 
upper atmosphere seems inescapable. The 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



II 9 



main uncertainty is one of degree, namely, 
whether any toroidal field comparable in 
magnitude with the earth's observed mag- 
netic field coexists in the atmosphere. This 
appears to depend on the available electric 
conductivity of the upper atmosphere, since 
increases in wind velocity with height seem 
assured on both theoretical and experi- 
mental grounds. In this connection it 
should also be noted that suitable winds 
can tend to neutralize the Hall currents 
accompanying toroidal electric currents in 
the atmosphere. As T. G. Cowling showed 
in 1932, under these conditions the effective 
conductivity transverse to a magnetic field 
in an ionized gas can approach that along 
the magnetic field. This would give 
enough conductivity to indicate closed-cir- 
cuit toroidal fields several or many gauss 
in strength. 

Daily Mean Meridional Winds 
E. H. Vestine 

During the past seventy years it has from 
time to time been suggested that winds in 
the upper atmosphere generate the time 
fluctuations of geomagnetism (including 
those of magnetic storms) by dynamo 
action. 

The essence of this idea is that the mo- 
tions of electrically conducting air across 
the lines of force of the geomagnetic field 
generate electric currents in the upper at- 
mosphere. The changing electric currents 
overhead then give rise to a fluctuating 
magnetic field at the ground. A number 
of studies have shown that the ordinary 
periodic daily change in the geomagnetic 
field is satisfactorily explained by this 
mechanism. But it has never been shown 
that the much larger occasional changes in 
field known as magnetic storms are to be 
explained in terms of probable vigorous 
motions of the upper air, although O. R. 
Wulf in a series of papers has recently re- 



newed considerable interest in this pos- 
sibility. An alternate incomplete theory of 
magnetic storms ascribes practically all ef- 
fects to solar streams of charged particles 
as a primary cause. According to this 
theory the initial phase of storms is due to 
electric currents flowing within the solar 
stream at a distance of a few earth radii. 
This current reverses and becomes stronger 
during the main phase, with leakage of 
charge to polar regions yielding electric 
driving forces for electric currents flow- 
ing in the atmosphere. 

A beginning was made in testing the 
dynamo theory of magnetic storms. From 
a study of upwards of 120 magnetic storms, 
it was found that about 75 per cent of field 
changes observed at the ground must be 
ascribed to electric currents in the atmos- 
phere, except possibly the part depending 
on universal time, because the observed 
changes at stations a few hundred kilo- 
meters apart are too great, in all latitudes, 
to be explained by electric currents flowing 
at distances several earth radii away. In 
co-operation with S. Chapman, it was 
noted that this condition is also effective 
during the initial phase of storms. Ac- 
cordingly, only a small fraction of the ob- 
served field pattern can reasonably be 
ascribed to electric currents flowing be- 
yond the atmosphere during a number of 
the hours of storm. 

As a more direct approach, an approxi- 
mate meridional wind system for monthly 
means of days of magnetic storm was de- 
rived. Such a wind system cannot be 
uniquely inferred from the geomagnetic 
data. A simple derived system of winds 
comprises rising air near the equator 
which flows poleward, then returns at 
lower atmospheric levels. It was found to 
resemble closely the system obtained from 
meteorology by W. W. Kellogg and G. F. 
Schilling, even to the detail of a seasonal 
term. The specific electric conductivity 



I20 CARNEGIE INSTITUTION OF WASHINGTON 

across the earth's magnetic field, estimated mental Station for the past year, during 
from ionospheric data for the F region, which time no solar-flare increases have 
however, is probably only about io~ 14 emu, been observed. A second meter with par- 
so that improbably great wind velocities aflin-lead pile, which should be twice as 
might be required at particular hours of a effective and much less heavy than the 
great magnetic storm. It is possible to in- first, has been constructed. Tests have 
crease the effective transverse conductivity been made which show that a reflecting 
for the required westward-flowing cur- electrometer and a photomultiplier can be 
rents by means of eastward-flowing zonal used to prevent the recording spot from 
winds throughout a layer. Calculations in going off the film if neutron increases 
progress suggest that the poleward-di- greater than about 300 per cent occur, 
rected electric field generated by eastward- Though this type of continuously record- 
flowing zonal winds will be used in gen- ing neutron meter has advantages of sim- 
erating toroidal electric currents, but if plicity, the demands on the insulation are 
some degree of north-south polarization high. So far it has not been found possible 
results, the effective transverse conductiv- either to eliminate leakage loss or to keep 
ity for westward current flow may be the loss constant for a period as long as a 
adequate. month or two. Tests are under way with 
Using a technique devised by J. A. Rat- a second counter to determine whether its 
cliffe, estimates were made of total ioniza- insulation characteristics can be made satis- 
tion of the F layers for Watheroo during factory. 

night hours of magnetic storm. It was Old cosmic-ray program. Continuous 

found that the average total ionization in operation of Carnegie Institution of Wash- 

the F region probably changes by less than ington Compton-Bennett meters was car- 

a factor of 2 during storm hours. This ried on at Godhavn (Greenland), Chel- 

conclusion is possibly also supported by tenham (Maryland), Huancayo (Peru), 

the fact that the average daily range in and Christchurch (New Zealand). Com- 

the quiet-day diurnal variation is the same plete reduction of bi-hourly values of the 

on days before and following solar flares, data from Cheltenham and Huancayo was 

and also on days preceding and during maintained. 

magnetic storms, so that the total ioniza- Secular change in burst frequency. The 

tion of the E region changes little during measurement of bursts from the Compton- 

storms. Consequently, any sources of ioni- Bennett records at Huancayo has been 

zation, such as ultraviolet, which would continued. Results of careful statistical 

increase conductivity in regions occupied analyses indicate that the burst frequency 

by the supposed electric currents and cause has chan £ ed b Y about 6o P er cent in the 

magnetic storms would have to be such interval *93fi-*95* and that the variation 

that E and F regions are little affected * us £ar w compatible with a 22-year cycle. 

1 r 1 1 • . .1 1 If this cyclic variation is substantiated by 

berore and during storms, in low and r / ... ,. . ; 

Mi . 1 future data, it would indicate an important 
e latitudes. . ' , . , r 

solar influence on the very high-energy part 

r^ r> t> of cosmic rays conceivably arising from 

Cosmic-Kay Research . ; . J rr* • 

a changing solar-magnetic moment. This 

S. E. Forbush | 3Urst mte a pp ears t0 De unaffected by 

Neutron meters. One neutron meter has magnetic storms and to be unrelated to 

been in operation at the Derwood Experi- sunspots. 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



121 



LABORATORY PHYSICS 



NUCLEAR PHYSICS 

N. P. Heydenburg, G. M. Temmer, and 
Student Collaborators 

The identification and complete specifi- 
cation of nuclear energy levels continues to 
be of considerable interest in the so-called 
"low-energy" region of nuclear physics. 
Once the energy and width, total angular 
momentum, parity, and possibly the iso- 
baric spin are determined for all energy 
levels of a nuclear species, that species is 
completely described and any successful 
nuclear model must fit into this empiri- 
cally established framework. The concept 
of "isobaric spin" just mentioned has 
moved into prominence in the past year 
because of the striking similarities of the 
level structures of mirror nuclei (indi- 
cating charge symmetry, i.e. equality of 
neutron-neutron forces and proton-proton 
forces), and even of triplets of isobars (in- 
dicating charge independence, i.e. equality 
of neutron-proton forces and proton-pro- 
ton forces). Corresponding levels are con- 
sidered members of a "multiplet," that is, 
different orientations of a spinlike quan- 
tity; hence the term isobaric spin. 

We have been making use of most of 
the methods available for the determina- 
tion of energy levels, such as elastic and 
inelastic scattering of charged particles, 
yields of various reaction products as a 
function of the accurately known incident 
energy, and angular distributions of neu- 
trons, protons, and gamma radiation com- 
ing from levels in the compound nucleus 
under study. Because of the availability of 
large currents of helium ions, we have con- 
centrated largely on using alpha particles 
as projectiles. Regions of excitation in the 
compound nuclei thus become accessible 
which can usually not be reached by other 
means. Furthermore, the fact that alpha 
particles have zero spin greatly simplifies 



the assignment of energy-level properties 
of the type discussed above. 

During the past year we have continued 
with our investigation of alpha scattering 
and alpha-induced disintegrations. Alpha 
scattering on nitrogen has been investi- 
gated, and the work on alpha-alpha scat- 
tering has been continued. Disintegration 
experiments with alpha particles have been 
done on nitrogen with the emission of pro- 
tons and on carbon of mass 13 with the 
emission of neutrons, and work has been 
continued on the disintegration of beryl- 
lium with the emission of neutrons. From 
these experiments, new information has 
been obtained on the energy-level schemes 
of the compound nuclei formed in each 
case. 

In our report for the year 1951-1952 
(Year Book No. 51), some results on alpha- 
alpha scattering were discussed. Summa- 
rizing these results, (1) it was found that 
the scattering cross sections for alpha ener- 
gies below 400 kev were in agreement with 
the theoretical calculations of Mott, assum- 
ing only Coulomb forces between the alpha 
particles; (2) no anomaly in the scattering 
was observed at the energy corresponding 
to the ground state of the beryllium nu- 
cleus of mass 8; (3) the effect of nuclear 
forces between alpha particles became in- 
creasingly apparent as the energy increased 
above 400 kev. The data for energies up 
to 3 Mev were analyzed in terms of S-wave 
phase shifts; the phase angle varied from 
180 at 400 kev to approximately 135 at 
3 Mev. 

During the past year we have made fur- 
ther observations on alpha-alpha scattering 
in order to determine whether the analysis 
of our data in terms of S-wave phase 
shifts was adequate, or whether phase 
shifts of higher angular momentum were 
also needed. D-wave phase shifts might be 



I22 CARNEGIE INSTITUTION OF WASHINGTON 

expected to be present even at 3 Mev (1.5 be desirable to follow this trend to higher 
Mev center of mass) if the broad first ex- energies than we had available, 
cited state of Be 8 at 2.94 Mev has a spin We have also extended our search for 
value / =2. an anomaly in the alpha-alpha scattering, 
Since the effect of a D wave vanishes at due to the effect of the ground state of Be 8 , 
the scattering angle = 27°22', it should to higher energies in order to cover the 
be possible to determine a unique value for somewhat higher generally accepted value 
the S-wave phase shift at this angle, if for the ground level of Be 8 (94.5 ±1.5 kev). 
absolute scattering cross sections are known Still no effect has been observed. This 
and if still higher-order phase shifts are enables us to set a lower limit to the life- 
negligible. Measurements at other angles time of the Be 8 ground state of 2X10" 17 
can then be used to determine any D-wave sec. It is known to be shorter than io" 15 
contribution. Absolute cross sections were sec from cosmic-ray evidence, 
measured by calibrating the scattering Continuing our program of study of 
chamber with alpha scattering in argon, alpha-particle-induced reactions, we have 
which was found to vary with energy and investigated the elastic scattering of alpha 
angle according to the Rutherford scat- particles by nitrogen and the reaction 
tering law over the energy region and N 14 + alpha -» F 18 -> O 17 '+ proton, 
angles of interest in alpha-alpha scatter- which leads to the same compound nu- 
ing. The alpha-beam currents were meas- cleus, F 18 , as the scattering. Only protons 
ured in an evacuated Faraday chamber leading to the ground state of O 17 were 
separated from the scattering volume by observed. By measuring the cross section 
a 2 X io _5 -inch nickel foil. A phase-shift for scattering at large angles and the yield 
analyzer was designed and constructed of protons, as a function of the energy of 
which could be set up to give simulta- the incident alpha particles, we have lo- 
neously combinations of S and D phase cated two new energy levels in F 18 . 
angles giving the observed scattering cross At a scattering angle of 156° 20' in the 
section at a given angle. A set of curves center-of-mass co-ordinates, rather sharp 
was then plotted, with one phase angle as pronounced dips occurred in the number 
the ordinate and the other as the abscissa, of scattered alphas at 2.88 Mev and at 3.05 
one for each scattering angle. If there is a Mev, followed by a sharp rise after the 
common intersection of these curves, a second dip, then a gradual return toward 
unique value of S and D phase shifts is the yield expected from Rutherford's scat- 
determined. At 2 Mev and below, only S tering law. The shape of these dips indi- 
phase shifts are needed to fit our data. At cated that the resonances were sufficiently 
2.5 and 3.0 Mev both S and D phase shifts broad and close together to cause inter- 
are necessary. The S phase angle varies ference effects which made it difficult to 
smoothly from 180 at 400 kev to 125 at determine the true resonance energies. The 
3.0 Mev. A D phase shift of — 3 gave proton yield from the alpha-proton reaction 
the best fit to the 3-Mev curve, although on nitrogen gave marked resonance peaks 
the difference between the experimental at close to the same energies as the dips in 
and theoretical curves at S = 2o° and 30° the scattering. From this curve the reso- 
was greater than our estimated experimen- nance energies were found to be at 2.935 
tal errors. This may indicate the presence and 3.140 Mev, corresponding to levels in 
of still higher-order phase shifts. It would F 18 at 6.69 and 6.85 Mev, respectively. The 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



I2 3 



proton yield also indicated the presence of 
a much broader level at 3.5 Mev or above. 
The location of these levels in F 18 is shown 
in figure 2, also the proton-yield curve and 
the alpha-scattering cross-section curve. 

In principle it is possible to determine 
the spin and parity which characterize 



and preliminary attempts at analysis did 
not yield unique values for the spin and 
parity. 

A preliminary report was given last year 
on the reaction Be 9 + alpha — > C 13 — > 
C 12 + neutron + gamma. In this reaction 
neutrons can be emitted, leaving C 12 in its 




2m„C- 



- 1.671 J / fi*0-64 
ie 



ENERGY LEVELS IN 



ENERGY LEVELS IN 0' 



Fig. 2. Schematic diagrams of energy-level systems of F 18 , C 13 , and O 17 investigated during the 
year. The observed yield curves shown have led to the discovery of new energy levels. The left- 
hand figure shows the results of the scattering of alpha particles on N 14 and the reaction: 
N 14 + a — ■> F 18 — > O 17 + proton. From these curves new energy levels in F 18 have been assigned 
at 6.69 and 6.85 Mev. The middle figure shows the yield curves for gamma and neutron emission 
from the reaction Be 9 + a — ■> C 13 — > C 12 + neutron + y. The resonance peaks in these curves lead 
to five new resonances in the nucleus C 13 . Also illustrated here are the two modes of disintegration 
of the excited C 13 nucleus, either by neutron emission to the excited state of C 12 then to the ground 
state by gamma emission, or directly to the ground state by emission of neutrons of higher energy. 
The right-hand figure shows the energy levels for the nucleus O 17 which have been assigned from 
the resonances appearing in the yield curve for neutrons from the reaction C 13 + a — > O 17 *-> 
O 16 + neutron. 



these levels by observations on the scatter- 
ing at a number of angles. Observations 
were made at angles 90°, 125 16', 137 
43', and 156° 20' (center of mass), as well 
as several angular distributions at critical 
energies. Because the nucleus N 14 has spin, 
/=i in its ground state, and because the 
observed levels are broad and close to- 
gether, the theoretical analysis is complex 



ground state or in its first excited state; 
C 12 excited then goes to the ground state 
by gamma-ray emission. Energy levels in 
the compound nucleus C 13 were reported 
at 1.92 and 2.62 Mev from observations on 
the neutron and gamma-ray yields as a 
function of the incident alpha energy. 
More careful observations of the neutron 
yields at both o° and 90° with respect to 



124 



CARNEGIE INSTITUTION OF WASHINGTON 



the incident alpha beam indicated reso- 
nances at 1.55, 2.27, and 2.84 Mev for neu- 
trons which were not observed for gamma 
rays. Hence these resonances appeared to 
be excited only for neutron emission to 
the ground state of C 12 . The energy-level 
scheme for C 13 is shown in figure 2, to- 
gether with the yield curves for neutrons 
and gamma rays. 

Studies have also been made on the re- 
action C 13 + alpha -> O 17 -» O 16 + neu- 
tron. The yield curve for neutrons from 
thin targets, enriched 23 per cent in C 13 , 
gave resonances at the following alpha en- 
ergies: 1.40, 2.23, 2.32, 2.45, 2.57, 2.68, 2.80, 
3.13, and 3.36 Mev. These resonances cor- 
respond to energy levels in the compound 
nucleus O 17 at 7.41, 8.04, 8.11, 8.21, 8.30, 
8.39, 8.48, 8.74, and 8.91 Mev, respectively. 
The energy-level scheme for O 17 and the 
observed neutron yield are shown in 
figure 2. 

During the year the Department's cyclo- 
tron has been undergoing some alterations. 
The magnetic field had never been prop- 
erly shimmed for extracting the beam 
from the circular path inside the dees. 
Careful field measurements have been 
made, and a rim shim has been added to 
keep the field up near the edge of the poles 
and to produce a strong fall-off field at the 
proper radius. Pyramidal shims have also 
been added to produce the proper decrease 
of field from the center for proper focusing 
of the beam as it spirals out from the cen- 
ter. By the end of this report year the 
cyclotron had been reassembled, and pre- 
liminary measurements indicate an im- 
provement in the amount of circulating 
deuteron beams at large radii. 

BIOPHYSICS 

P. H. Abelson, E. T. Bolton, R. J. Britten, 
D. B. Cowie, and R. B. Roberts 

Six years of work in biophysics have 
only increased our conviction that many 



advantages accrue from the investigation 
of biological problems in a physics depart- 
ment. The points of interest in the field 
of biology are somewhat different for the 
physicist from what they are for the biolo- 
gist, and the approach to a given problem 
may be different. Even after some years 
in the field, the physicist is still a "for- 
eigner" and observes certain peculiarities 
which are too familiar for the "local citi- 
zens" to notice. Also, the biological work, 
currently a quantitative study of "flow dia- 
grams" for various chemical elements in- 
volved in the biosynthesis of proteins and 
nucleic acid, gains perspective when con- 
stantly viewed in comparison with the 
other problems under study in the Depart- 
ment. 

The interchange of ideas and techniques 
is not a one-way process. The biophysics 
group has aided the study of the age of 
rocks by helping to initiate the use of ion- 
exchange columns in mineral separation 
for work at the microgram level needed in 
the radioactive dating of very ancient igne- 
ous rocks. It has also stimulated an ex- 
amination of ancient rocks for organic re- 
mains. We believe its main contribution 
to the rest of the Department, however, 
lies in keeping them aware of the nature 
and complexity and elegant regularity of 
processes in living matter, which cannot 
fail to broaden their view of the universe. 

A specific program in biophysics was 
initiated at the Department in 1946 as the 
outcome of a long period of collaboration 
with biologists in the use of radioactive 
tracers. For the past four years, the group 
has directed its efforts toward studies 
which might increase understanding of 
the biosynthesis of proteins and nucleic 
acids. This central problem of biology can 
be attacked at many levels and by the use 
of many techniques. One particular ap- 
proach, a study of the biosynthesis of the 
amino acids and other substructures from 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



125 



which proteins and nucleic acids are as- 
sembled, has received the major emphasis 
for some time. 

During the past year the knowledge 
previously gained was amplified and con- 
firmed by extensive use of various C 14 - 
labeled compounds. The pathways deter- 
mined with C 14 2 as a tracer were also 
demonstrated with C 14 -labeled acetate and 
C 14 -glucose. The use of many different 
tracer compounds also permitted quantita- 
tive determinations of the flow through 
the different reaction sequences of biosyn- 
thesis. As a result of this work, it is now 
possible to account quantitatively for most 
of the carbon which the growing cells of 
Escherichia coli convert from glucose into 
cellular material. 

The knowledge gained in these studies 
of the biosynthesis of relatively simple 
molecules can be applied in many ways to 
the problems of the synthesis of the com- 
plex macromolecules of protein and nucleic 
acid. These large molecules are assembled 
from their simpler components, which are 
supplied in the required quantities by ap- 
parently independent systems. One ques- 
tion which now appears to be open to ex- 
perimental study is the nature of the 
controlling mechanisms which co-ordinate 
the rates at which the needed materials 
are formed. An approach to this problem 
has already been made by examining the 
material lost from growing cells. This 
work has demonstrated that normally a 
very precise balance between synthesis and 
utilization is achieved by the cell and no 
building blocks are synthesized in excess 
of the requirements. Under certain condi- 
tions this balance can be upset and large 
quantities of various materials are synthe- 
sized only to be excreted into the medium. 

Another type of study utilizing this 
knowledge of the synthetic pathways has 
indicated the importance of peptides in 
protein synthesis. Kinetic measurements 



seem possible which would determine the 
extent to which peptides serve as inter- 
mediates. It appears more profitable to 
proceed in these directions than to attempt 
to work out the remaining puzzles of 
amino acid synthesis. 

The wide variety of experiments which 
have been carried out could not be re- 
ported adequately in the usual technical 
journals. Consequently, it has been neces- 
sary to devote a large part of the year's 
work to assembling the information in 
the form of a monograph which will be 
submitted to the Carnegie Institution for 
publication. This book will mark the 
climax of one phase of the biophysics 
program. 

Amino Acid Synthesis in 
Escherichia coli 

The isotopic competition method has 
been used with a variety of C 14 -labeled 
molecules to determine the pathways of 
synthesis for fifteen of the nineteen amino 
acids found in the proteins of Escherichia 
coli. This method consists in making more 
than one source of carbon available to the 
cell, and labeling one of the carbon sources 
with C 14 so that the way in which it is 
utilized by the cell can be determined. It 
is frequently observed that the cell selects 
one of the carbon sources for certain spe- 
cific biosynthesis, using other carbon for 
the rest of the cell material. 

As an example, the amino acids threo- 
nine, isoleucine, methionine, lysine, and 
diaminopimelic acid all derive the same 
quantity of carbon per molecule from CO2 
as does aspartic acid. Consequently, they 
may be grouped as the "aspartic family." 
Furthermore, the location of the carbon 
derived from CO2 corresponds throughout 
the family. The same relationships are 
shown when C 14 -glucose, C 14 -acetate, or 
C 14 -aspartic acid is used as tracer. No one 



126 



CARNEGIE INSTITUTION OF WASHINGTON 



of the family except aspartic acid, however, 
gives rise to all the others, a fact which 
shows that aspartic acid serves as the par- 
ent substance for the whole group. 

C 14 -labeled glucose, acetate, carbon di- 
oxide, and amino acids have all been used 
as tracers in these studies. Consequently, 
the pathways have been established and 
checked by several different methods. In 



KC-^WVSPARTIC ACID- 



S' 4 ''y * NUCL 



EIC ACID, PYRIMIDINES 
4.1 



-►ASPARTIC ACID 
11.5 



NH 3 



■►LYSINE 
5.6 



-4>— »-DIAMINOPIMELIC ACID 
kL 0-4 



HOMOSERINE 



-♦-HOMOCYSTINE— -^METHIONINE 

■ 3 2 

CH 3 3Z 



THREONINE 

NH 3 k.NH 3 

aNH-> BUTYRIC ACID * » <X KETO BUTYRIC ACID 

I 

Cp Wot 



-♦THREONINE 
5.0 



KETO /3 METHYL VALERIC ACID 



NH, 



} 



ISOLEUCINE 
5.0 



Fig. 3. Aspartic acid is formed as a product 
of the Krebs cycle and is used by the cell in the 
synthesis of a number of other products. More 
than 50 per cent of the carbon utilized in pro- 
tein synthesis is found in aspartic acid, glutamic 
acid, and their products. The numbers indicate 
the flow as observed in E. coli (micromoles per 
gram dry cells per 100 seconds). 

addition, glucose labeled with C 14 in the 
1 or 2 carbon position has given additional 
information on the pathways of carbohy- 
drate metabolism. C 14 -formate and C 14 - 
formaldehyde were also used to a limited 
extent in examining the formation of 
nucleic acids. 

The sequence of reactions giving rise to 
the aspartic family is shown in figure 3. 
The presence of homoserine as an inter- 
mediate was demonstrated both by the 
competition method (see p. 130) and by 



observing the production of radioactive 
homoserine (from C 14 -glucose) when C 12 - 
homoserine was added to the medium. As- 
partic acid also contributes to the synthe- 
sis of pyrimidines, thereby linking amino 
acid and nucleic acid synthesis. 



KC— =^-»-GLUTAMIC ACID \ » GLUTAMIC ACID 
I 11.8 



•PEPTIDES (GLUTATHIONE) 



ACETATE 



•N ACETYLGLUTAMIC 
H 3- 



O 



ACETYLORNI 



ACETATE 
THINE— «^-*- ORNITHINE • 



CITRULUNE-jr-*-ARGININE 



CO, 



-tt-*-ARGINI 
' 4.9 



Fig. 4. Glutamic acid, a product of the Krebs 
cycle, is transformed by a series of reactions 
to form proline and arginine. The numbers in- 
dicate the flow into the various products in 
micromoles per gram dry cells per 100 seconds 
as observed with exponentially growing E. coli, 
using radioactive carbon-14. 




♦-NUCLEIC ACID 
PURINES 



GLUTATHIONE 



Fig. 5. Serine is the precursor of glycine and 
cystine and is also utilized in lipid synthesis (not 
shown). The glycine is used in part for nucleic 
acid synthesis; serine thus acts as a common 
precursor of proteins, nucleic acids, and lipids. 
The flows indicated are in micromoles per gram 
dry cells per 100 seconds as observed in exponen- 
tially growing E. coli, using carbon-14 as a radio- 
active tracer. 

Glutamic acid gives rise to proline and 
arginine, as shown in figure 4. It is also 
used in the formation of peptides, particu- 
larly glutathione, which is abundant in 
the cells. 

Serine is the precursor of glycine and 
cystine, as shown in figure 5. The glycine 
and cystine thus formed are utilized in the 
formation of glutathione. Glycine is also 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



127 



used in the synthesis of purines, and thus 
it provides a second link between proteins 
and nucleic acids. 

Pyruvic acid is utilized in the synthesis 
of alanine, valine, and leucine, as indicated 
in figure 6. The conversion of valine to 
leucine apparently proceeds by decarboxy- 
lation and addition of acetate. In addition 
to these major pathways of amino acid 



scheme, glucose is converted to pyruvic 
acid by way of a series of reactions involv- 
ing phosphorylated intermediates. The 
pyruvic acid then enters the Krebs cycle 
(fig. 7) and is oxidized to CO2. 

Although the operation of the Krebs 
cycle in bacteria has been disputed, it 



PYRUVIC ACID 



CO? 

y * ■ VALINE <£ -^LEUCINE 

f 5.9 7.9 




TO MEDIUM 



LIPIDS 



Fig. 6. Pyruvic acid plays an important role 
in the synthetic activities of cells. The flow of 
pyruvic acid to form alanine, valine, and leucine 
and other products is given in micromoles per 
gram dry cells per 100 seconds as observed in 
exponentially growing E. coli. 

synthesis, alternate pathways have been 
shown to exist. In the usual medium these 
pathways are unimportant, contributing 
only a few per cent of the material. In 
certain other media, however, they assume 
major importance. The existence of these 
potentially available mechanisms might 
cause very misleading interpretations of 
mutant requirements. 

These amino acids account for 90 per 
cent of the protein carbon or 54 per cent of 
the total carbon incorporated by the cell. 
Consequently, it was of considerable in- 
terest to relate the quantities of amino acid 
formed to the total utilization of glucose. 

For some time the degradation of glu- 
cose to CO2 and water has been believed 
to proceed by two mechanisms working in 
series. In the Embden-MeyerhofT glycolytic 




Fig. 7. In the Krebs tricarboxylic acid cycle, 
C0 2 condenses with pyruvic acid to form oxalo- 
acetic acid. A portion of the oxaloacetic acid is 
converted to aspartic acid, partly by transamina- 
tion and partly by animation of fumaric acid. 
Another portion of the oxaloacetic acid condenses 
with acetic acid to form citric acid. A further 
sequence of reactions converts the citric acid to 
a keto glutaric acid, which serves as the pre- 
cursor of glutamic acid. In addition, a part of 
the a keto glutaric acid is decarboxylated to yield 
the dicarboxylic acids, thereby regenerating ox- 
aloacetic acid. The carbon atoms are lettered to 
facilitate identification: the input carbons are 
designated A, B, C, D, E, F, and the carbons of 
aspartic acid are labeled W, X, Y, Z. When the 
flow in the various branches of the cycle is 
known, the radioactivity of the W, X, Y, Z car- 
bons can be calculated from the known radioac- 
tivity of the input carbons. 

seemed a plausible mechanism for the in- 
corporation of C0 2 and acetate into the 
glutamic and aspartic families of amino 
acids. It was found that predictions based 
on the Krebs cycle were checked precisely 
by the observed incorporation of various 
tracers into the amino acids. Furthermore, 



128 



CARNEGIE INSTITUTION OF WASHINGTON 



measurements of the incorporation of one 
tracer (C 14 2 ) specified very definite flows 
in the cycle which could be verified inde- 
pendently by measuring the incorporation 
of other tracer compounds. Figure 8 shows 
a typical flow pattern for cells growing ex- 
ponentially with glucose, acetate, and car- 
bon dioxide as carbon sources. 

C 14 -acetate provides a particularly use- 
ful measure of the flow in the cycle. With 
this tracer it was possible to observe in- 



IC^ »• ACETIC 



I 

I 

I 

t 
ACETIC 

+ 
ACETIC 

I 

I 

I 

I 

I 




Fig. 8. Flow of carbon in the various branches 
of the Krebs cycle, in micromoles per gram dry 
weight of cell per ioo seconds. This flow pat- 
tern was observed with E. coli growing exponen- 
tially (37 ° C aerated) with glucose acetate and 
C0 2 as carbon sources. Other organisms and 
other conditions show altered flows. The dashed 
lines indicate the dicarboxylic acid cycle, which 
is not significant in E. colt. 

creased flow rates as the cells started to 
grow and came out of the lag phase into 
exponential growth. Other carbon sources, 
such as glutamic acid, added to the glu- 
cose medium caused an immediate altera- 
tion of the flow patterns. Still other 
changes in the flow patterns were observed 
when cells were adapted to use succinic 
acid as the sole carbon source. 

The flow in the Krebs cycle can be re- 
lated to the total utilization of glucose. 
Figure 9 shows that only a small fraction 
of the glucose carbon enters the Krebs 



cycle and that the net C0 2 produced by 
the cycle is less than 4 per cent of the total 
C0 2 production of the cell. Thus in these 
growing organisms, the cycle functions 
mainly as a mechanism for amino acid 
synthesis and is of only minor importance 
in the oxidation of glucose and the produc- 
tion of energy. 

Recently several investigators in other 
laboratories have found that a part of the 



420 GLUCOSE- 



PYRUVIC ACID 




50% C0 2 

30% INCORPORATED 
20% RELEASED TO MEDIUM, 
MAINLY ACETATE 

NUCLEIC ACID PENTOSE 

SERINE FAMILY 

PYRUVIC AMINO ACIDS 

MEDIUM 

LIPIDS 



ASPARTIC FAMILY 
GLUTAMIC FAMILY 



Fig. 9. When glucose is supplied to exponen- 
tially growing E. coli as the sole carbon source, 
it is utilized at a rate of 420 micromoles per gram 
dry cells per 100 seconds. Approximately 30 
per cent of the carbon is incorporated, the re- 
mainder being released as C0 2 , acetate, and a 
number of other compounds. The synthesis of 
the nucleic acid and the various families of amino 
acids accounts for a large proportion of the carbon 
incorporated. These reactions, however, account 
for only a small fraction of the total C0 2 pro- 
duced from glucose. The flows indicated are 
given in micromoles per gram dry cells per 
100 seconds. 

glucose is metabolized by a process which 
oxidizes the i-carbon. Investigations car- 
ried out during the past year with C-i- 
labeled glucose show that this oxidation 
pathway can contribute only minor quanti- 
ties of carbon to the amino acids, as they 
contain the full quantity of C-i carbon 
which would be expected from the Meyer- 
hoff glycolytic system. The oxidation path- 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



129 



way, however, might help to explain the 
amount of C0 2 produced, which appears 
too large to be accounted for by the other 
pathways. 

Nucleic Acid Synthesis 

The origins of the carbon of the various 
constituents of bacterial nucleic acid are 
now known, and some features of the 
pathways for synthesis of nucleic acid have 



PURINE 


6 






^ C \ 5 

NT C — N 

I i C 8 
1 s> 


CARBON ATOM 

2 AND 8 


SOURCE 
FORMATE 


C. C — N 


4 AND 5 
6 


GLYCINE 
C0 2 


PYRIMIDINE 


6 






N /C X * 


CARBON ATOM 


SOURCE 


1 1 


2 


C0 2 


i'^/'. 


4, 5, AND 6 


ASPARTIC ACID 



Fig. 10. Sources of the carbon atoms of the 
purines and pyrimidines in E. coli. The purines 
and pyrimidines are organic ring compounds 
which, together with a sugar phosphate, make 
up the nucleic acids found in all living things. 
Although the details of the way in which any 
species makes these compounds from its food- 
stuffs are not yet known, the usual sources of 
their carbon atoms are known. The ring struc- 
ture of the compounds and the simple foodstuffs 
from which each carbon atom is derived are 
shown in this figure. 

been established in this laboratory. Two of 
the purines, adenine and guanine, con- 
tain five carbon atoms. One of these, car- 
bon-6, is derived from the carbon dioxide 
of the culture medium. Two others, car- 
bons 2 and 8, are derived from formate (or 
formaldehyde), and the remaining two, 
carbons 4 and 5, from the amino acid gly- 
cine (fig. 10). Other carbon compounds 
may contribute carbon to the bacterial 
purines. In some cases the contribution 
occurs after the alternative source has been 



converted to one ot the primary sources; 
in others, the compounds are utilized with 
only minor alterations. Thus, serine and 
threonine are first converted to glycine, 
and the glycine so formed is actually used 
in purine synthesis. Adenine serves as a 
source for either compound of the bac- 
terial nucleic acid; guanine provides only 
the required guanine. The pyrimidines 
cytosine and uracil contain four carbon 
atoms. One of these, carbon-2, is derived 
from the carbon dioxide of the culture 
medium. Aspartic acid accounts for the 
remaining three carbon atoms, carbons 4, 
5, and 6 (fig. 10). Since aspartic acid itself 
may be synthesized in part from carbon 
dioxide, carbon dioxide can supply more 
than one carbon of the pyrimidines. Exog- 
enous uracil is also utilized in nucleic acid 
synthesis. The five-carbon sugar portions, 
ribose and desoxyribose, of the nucleic 
acids are derived entirely from the glucose 
of the culture medium, when cells are 
adapted to utilize glucose. When they are 
adapted to utilize other carbon sources, 
such as succinic or a keto glutaric acids, 
the riboses are, of course, derived from 
these sources. Even in these cases, how- 
ever, the pattern of carbon dioxide incor- 
poration into the purines and pyrimidines 
remains similar to that described above. 

Studies of nucleic acid synthesis with 
C 14 -labeled compounds may all be inter- 
preted in accord with these findings. For 
example, C 14 -acetate contributes radioac- 
tivity largely to the pyrimidines of bacterial 
nucleic acid. The purines are very weakly 
labeled, since acetate cannot readily be con- 
verted to C0 2 , formate, or glycine. Analy- 
ses of the radioactivity data from a typical 
experiment showed that the quantity of 
radioactivity found in the pyrimidines after 
acetate labeling was exactly equivalent to 
the amount expected if the labeling oc- 
curred by way of aspartic acid. 



130 



CARNEGIE INSTITUTION OF WASHINGTON 



These studies, together with the results 
of isotopic competition studies, provide a 
background against which a more com- 
plete picture of nucleic acid synthesis may 
be drawn. They have also revealed an in- 
timate biochemical connection between 
proteins and nucleic acid during the 
growth of bacteria: glycine and aspartic 
acid are precursors of both materials. The 
Krebs cycle by which aspartic acid is pro- 
duced, therefore, serves as one of the mech- 
anisms which link together the synthesis 
of protein and nucleic acid. 

The Competition Method 

Observations of the selective utilization 
of various carbon substrates for the syn- 
thesis of protein amino acids have led to 
the elucidation of the main steps of syn- 
thesis for the carbon skeleton of 90 per 
cent of amino acid residues of Escherichia 
coli protein. The method which has been 
used has been termed "isotopic competi- 
tion." It may be considered that, in whole 
or in part, the carbon chain of the added 
substrate molecule competes with carbon 
from glucose for a position in the final 
protoplasm of the cell. Either the glucose 
(always present in the system under study, 
as principal carbon and energy source) or 
the added substrate may be labeled with 
the radioactive isotope C 14 . 

The fate of the radioactive C 14 , or by 
difference the C 12 , may be determined by 
splitting the protein into its constituent 
amino acids, and in some cases by degrad- 
ing the amino acid molecules, carbon atom 
by carbon atom. When the additional sub- 
strate (competitor) is labeled with C 14 , a 
greater sensitivity for minor carbon path- 
ways is obtained. If the competitor is 
unavailable with a C 14 label, however, the 
experiment may be performed with radio- 
active glucose or C 14 2 and an unlabeled 
competitor, thus opening up the whole 



available supply of organic compounds for 
this type of experiment. 

The particular value of the competition 
method results from the specific response 
of the cells to certain substrates. Though 
E. coli may be adapted to many substrates 
so as to make use of them as sole carbon 
and energy sources, there is no evidence 
that adaptation plays a role in competition. 
The response is due to the changed con- 
centration of the chemicals in the environ- 
ment rather than to any change in the 
enzymatic complement of the cells. Dur- 
ing an exposure of one or two generations 
of rapid growth a substance will, in gen- 
eral, be utilized only in pathways where 
it or a very similar compound normally 
occurs. Consequently, the competition 
method gives information about normal 
pathways rather than pathways requiring 
adaptation. 

Some care has been taken to ascertain 
that the presence of competitors has not 
so changed the environment that the cell 
chemistry operates in wholly new ways. 
Cross-check experiments with a wide vari- 
ety of tracer compounds and with compet- 
itors at various points along a particular 
pathway have shown that the biochemical 
processes have a great deal of stability. In 
only a few cases have major alternative 
pathways been established; in other cases, 
changes in the rates of flow of carbon have 
been observed. 

Extracellular Metabolic Products 

For the studies of the pathways of amino 
acid synthesis it has not been necessary to 
have a detailed understanding of the 
mechanism of the competition method. In- 
vestigations of the mechanism, however, 
carried out by observations of the com- 
pounds appearing in the growth medium, 
have given insight into the cell chemistry, 
and have opened up the possibility of 



DEPARTMENT OF TERRESTRIAL MAGNETISM ^ 

studying some aspects of its control and ternally synthesized compound in the pro- 
organization, tein. 

When E. coli is grown aerobically with In this type of experiment, if unlabeled 
glucose as substrate, about 70 per cent of glutamic acid, aspartic acid, glycine, ala- 
the glucose carbon appears as extracellular nine, or valine is present as a competitor, 
products. The major products are carbon it appears in the medium containing la- 
dioxide (50 per cent) and acetate (13 per beled glucose carbon. The amount of the 
cent). The remaining small percentage of labeled compound indicates that the rate 
the carbon appears in a complex spectrum of synthesis of the compound from glu- 
of compounds. About 40 of these have cose has not been strongly reduced. The 
been resolved, and several have been iden- presence of unlabeled arginine, leucine, iso- 
tified. Normally, none of these compounds leucine, cystine, and lysine as competitors 
is predominant, and the amount of any in- causes the respective labeled compounds 
dividual compound appearing, such as as- to appear in small quantities, a result 
partic or glutamic acid, is very small — less which indicates that the rate of synthesis 
than 1 per cent of the amount synthesized is much reduced by the presence of the 
by the cells. This finding demonstrates a substance as competitor. On the other 
high degree of precision in the control of hand, no trace of radioactivity appears in 
the relative rates of synthesis of these com- the medium in the following amino acids 
pounds which are used as building blocks when they are present as unlabeled com- 
for protein synthesis. Certain variations in petitors : proline, threonine, methionine, 
culture conditions may cause a few of these and serine. Thus the rate of synthesis of 
compounds to become prominent, indicat- these compounds has been reduced nearly 
ing an imbalance in rate of synthesis. to zero by the presence of the competitor. 

Most amino acids are utilized by E. coli In some cases precursors of the compet- 

for protein synthesis, when they are avail- itor appear in the medium; for instance, 

able in the medium. In all these cases the fumaric and succinic acids are produced 

incorporation of glucose carbon into the from glucose carbon when aspartic acid is 

particular protein amino acid is strongly present as a competitor. This case will be 

reduced. In some cases the internally syn- discussed in more detail below. Thus, the 

thesized amino acids or compounds which observation of the compounds appearing 

occur near by on the synthetic pathways ap- in the medium opens up the possibility of 

pear in the growth medium. identifying hitherto unsuspected interme- 

It has been possible to observe, and in diates. It also offers the possibility of dem- 

most cases identify, the compounds that onstrating that a suspected intermediate is 

are produced in the growth medium in re- actually synthesized by the cells. Among a 

sponse to the presence of these competitors, series of suspected intermediates, the fol- 

If the cells are grown on randomly labeled lowing appear in the medium labeled from 

glucose and the competitor is not labeled, glucose when the unlabeled competitor is 

substances which derive carbon from the present: succinic, fumaric, and malic acids, 

glucose, and, therefore, have actually been and homoserine. Another group of sus- 

synthesized by the cells, will be radioactive, pected intermediates which are effective 

In this way it has been determined whether competitors gave negative results — that is, 

an effective competitor stops the synthesis no trace of radioactive compounds in the 

of a compound or simply replaces the in- medium. 



132 



CARNEGIE INSTITUTION OF WASHINGTON 



The observation that succinic, fumaric, 
and malic acids appear labeled in the me- 
dium when the unlabeled compound is 
present is particularly useful, since these 
are relatively ineffective as competitors and 
the positive demonstration of their synthe- 
sis by the cells strengthens the deductions 
about the Krebs cycle. The negative re- 
sults from the other suspected interme- 
diates do not supply decisive evidence on 
their role as intermediates, since threonine, 
which is synthesized by the cells and is an 
intermediate in the synthesis of isoleucine, 
also gives a negative result. 

Further information about the opera- 
tion of the Krebs cycle has been obtained 
by comparing two experiments in which 
aspartic acid was the competitor. In one 
case the glucose was labeled, and in the 
other case the glucose was nonradioactive 
but labeled C0 2 was present. With the 
glucose labeled, radioactive aspartic, fu- 
maric, and succinic acids appeared in the 
medium. When the C0 2 was labeled, 
however, radioactivity appeared only in 
the aspartic and fumaric acids. These re- 
sults indicate (i) that fumaric acid is the 
symmetrical intermediate which is needed 
to explain the appearance of C 14 from 
C 14 2 in both terminal carbons of aspartic 
acid, and (2) that fumaric acid is not 
directly converted to succinic acid in these 
growing cells. 

The excess of fumaric acid is presumably 
the cause of the discharge of succinic acid 
to the medium, particularly since fumaric 
acid added to the medium produces the 
same result. This result cannot, however, 
be interpreted in terms of the reversal of 
the normal reaction succinic — > fumaric, 
because very little of the radioactivity of 
fumaric acid appears in succinic acid. Ac- 
cordingly, it seems that the normal reac- 
tion is strongly inhibited, possibly because 
the enzyme is saturated with fumaric acid 



and no sites are available for adsorption 
of succinic acid. 

With a relatively small perturbation of 
the chemistry of exponentially growing 
bacterial cells, considerable insight has been 
obtained into a reaction step between two 
transient intermediate compounds. The 
opportunity to make observations of equi- 
librium constants, and possibly other ki- 
netic aspects of a particular reaction, in an 
only slightly perturbed growing organism 
may have considerable biological impor- 
tance. 

Composition of Escherichia coli 

Further information on the composition 
of the various fractions which can be ex- 
tracted from Escherichia coli has been ac- 
cumulated during the year. Observations 
of the total uptake of a radioactive tracer 
give a crude measure of metabolic activ- 
ity. Much more information is obtained if 
it is possible to follow the tracer into par- 
ticular compounds formed by the cells. In 
cases where this is not feasible, it is desir- 
able at least to observe the distribution of 
the tracer in various broad classes of com- 
pounds, which are separated by chemical 
fractionation. 

The fractionation procedure involves ex- 
tracting with cold trichloracetic acid 
(TCA), followed by alcohol and by hot 
TCA, thereby yielding three soluble frac- 
tions and a residual insoluble fraction. 

The cold-TCA-soluble fraction contains 
most of the transient intermediates of the 
cell. Chromatography reveals more than 
twenty components (mostly unidentified), 
among which glutathione is particularly 
prominent. Many of the components re- 
act with ninhydrin, but, as they do not 
correspond to known amino acids, they are 
probably peptides. After hydrolysis, glu- 
tamic acid, glycine, cystine, and alanine 
appear prominently. 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



J 33 



The alcohol-soluble fraction can be re- 
solved into two components, one of which 
is lipid or phospholipid and the other ap- 
pears to be protein. It seems likely that 
these are associated in the cell as a loose 
complex which is broken down by chro- 
matography. Roughly one-sixth of the cel- 
lular protein appears in this fraction. Fur- 
thermore, this protein has quite a different 
metabolism from the rest of the protein of 

TABLE 5 
Distribution of radioactivity from various 

TRACERS 





C14- 


C14- 




glu- 


ace- 


C> 4 2 S 3 4 P 32 4 


cose 


tate 





Total cell 100 100 100 100 100 

Metabolic 

intermediates 8 5 4 25 20 

Lipids, 

phospholipids 15 43 15 

Nucleic acids 18 4 33 63 

Alcohol-soluble 

proteins 10 8 11 12 

Residual proteins . . 49 40 52 63 2 



the cell, as can be shown by kinetic experi- 
ments (see below). 

The hot-TCA-soluble fraction (after hy- 
drolysis) yields only the constituents of 
nucleic acid. The residual insoluble ma- 
terial is protein. The distribution of radio- 
activity from various tracers among the 
fractions is shown in table 5. The amino 
acid composition of the protein was deter- 
mined by growing cells with C 14 -glucose 
as a sole carbon source and measuring the 
radioactive content of the separated amino 
acids, as shown in table 6. 

Utilization of Sulfur Reservoirs for 
Protein Synthesis 

Escherichia coli utilizes sulfur for pep- 
tide and protein synthesis by converting 
inorganic sulfur into the amino acids 
cysteine and methionine. These bacteria 
also utilize other forms of sulfur, includ- 
ing the amino acids, for protein synthesis. 
Once the sulfur supplied in the medium 
has been converted into cell components, it 



TABLE 6 
Amino acid content of Escherichia coli protein hydrolysates 



Amino acid 


No. 
C 


Mol. 
wt. 


C 14 AA 

C 14 val. 


Hydrolysate 
carbon 
- (%) 


Mol. 
(%) 


Percentage 

of E. coli 

protein 


Probable 
error 
(%) 


Alanine 


3 


89 


1.34 


8.52 


13.1 


8.72 


3 


Arginine 


6 


174 


1.00 


6.36 


4.9 


7.16 


5 


Aspartic acid 


4 


133 


1.56 


9.92 


11.5 


12.3 


5 


Cysteic acid 


3 


169 


0.14 


0.90 


1.4 


1.9 


25 


Glutamic acid 


5 


147 

75 


2.00 
0.49 


12.7 
3.1 


11.8 

7.2 


14.2 
3.8 


3 


Glycine 


2 


10 


Histidine 


6 


155 


0.15 


0.95 


0.7 


0.80 


50 


Isoleucine 


6 


131 


1.08 


6.9 


5.3 


5.6 


25 


Leucine 


6 


131 


1.62 


10.3 


7.9 


8.4 


25 


Lysine 


6 


146 


1.16 


7.37 


5.63 


6.60 


5 


Methionine 


5 


149 


0.26 


1.65 


1.53 


1.9 


10 


Phenyl-alanine 


9 


165 


0.60 


3.8 


2.0 


2.7 


50 


Proline 


5 


115 


0.76 


4.82 


4.46 


4.17 


3 


Serine 


3 


105 


0.66 


4.2 


6.5 


5.2 


10 


Threonine 


4 


119 


0.68 


4.32 


5.0 


4.73 


5 


Tyrosine 


9 


181 


0.71 


4.7 


2.3 


3.6 


25 


Valine 


5 


117 


1.00 


6.36 


5.9 


5.45 


5 



134 



CARNEGIE INSTITUTION OF WASHINGTON 



becomes a relatively stable part of the 
protoplasm, undergoing exchange only un- 
der special conditions and then to a very 
limited degree from the TCA-soluble frac- 
tion. Glutathione is the chief sulfur con- 
stituent of this fraction. Last year it was 
reported that the glutathione in the cell 
could serve as a source of sulfur for the 
proteins. Thus, a stepwise sequence of 
synthesis from the sulfur of the medium, 
to glutathione, to protein was established. 
In the past year it has been found that 
during sulfur starvation another chemi- 
cally distinct fraction of the cell, the alco- 
hol-soluble protein, may also serve as a 
source of residual protein sulfur. 

Ordinarily, the sulfur composition of 
E. coli is a very constant quality. One- 
quarter of the sulfur of the cell is contained 
in the TCA fraction and three-quarters in 
the proteins. The sulfur in the proteins is 
contained in the amino acids methionine 
and cysteine in the proportion 2 to i. The 
alcohol-soluble proteins, which are quali- 
tatively different from the residual pro- 
teins, constitute about 16 per cent of the 
total residual proteins of the cell. The 
sulfur content of the bacteria may be 
varied, and the distribution of sulfur with- 
in the cell altered, by reducing the level of 
sulfur supplied in the culture medium, or 
by providing chemical forms of sulfur 
which do not satisfy all the needs of the 
cell. Both conditions result in sulfur star- 
vation and eventual cessation of growth. 
Immediately after the sulfur supply has 
been shut off by one of these means, cells 
continue to grow at a normal rate. After 
a relatively short period of development, 
the growth rate falls with remarkable ab- 
ruptness to one-tenth its former value. 
Eventually growth stops. During these 
periods of growth change, the sulfur con- 
tent of the various chemical fractions of 
the cell also changes. When the exogenous 



sulfur supply is removed and no sulfur is 
available, the sulfur in the TCA fraction 
decreases sharply, while the protein sulfur 
increases. Thus, the sulfur of glutathione 
is drawn upon for protein synthesis, acting 
as a reservoir. Protein synthesis during 
this time occurs at a nearly normal rate. 
At the instant when this reservoir has 
emptied and the growth rate is altered, the 
alcohol-soluble protein undergoes deple- 
tion of its sulfur. The alcohol-soluble sul- 
fur is then transferred to the residual pro- 
tein. The alcohol-soluble fraction also 
serves as a reservoir for sulfur, being 
drawn upon at a rate proportional to 
growth. Experiments with C 14 -labeled al- 
cohol-soluble protein show that a flow of 
carbon from this material to the residual 
proteins is coincident with the flow of sul- 
fur. When growth has ceased, neither car- 
bon nor sulfur is converted into residual 
protein, nor is either of these elements lost 
from the cell. The methionine-cysteine 
ratio in the residual proteins remains con- 
stant all through these activities. 

Experiments in which sulfur-deficient 
media have been reconstituted at points 
along the response sequence have shown 
that new protein is made from sulfate 
whether sulfate is added during the deple- 
tion of the TCA reservoir or after both 
reservoirs have been largely emptied. On 
the other hand, reconstitution of the me- 
dium with methionine after the TCA res- 
ervoir is empty has little effect on growth. 
Methionine added to the medium at any 
time before the instant of depletion of the 
TCA-soluble fraction, however, results in 
normal growth and the use of methionine 
for protein synthesis. 

These results add to knowledge of the 
metabolism of sulfur by E. coli. They are 
of particular significance for the study of 
the process of protein synthesis, since they 
demonstrate that certain components of the 
cell may be sacrificed in times of need to 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



135 



the manufacture of residual protein. One 
of these components is a tri-peptide and 
another is itself a protein or a very complex 
polypeptide. The experiments in which 
deficient media were reconstituted indicate 
that sulfur-starved cells preserve their pro- 
tein-making apparatus and that it will 
operate effectively provided it has the ap- 
propriate raw materials with which to 
work. They also show that even during 
starvation protein synthesis remains an or- 
derly process: it will not take place with 
methionine as the sole available supply of 
sulfur; when it does take place, proteins 
with methionine and cysteine contents in 
the ration 2 to 1 are made. Finally, these 
experiments have provided a model system 
in which it should be possible critically 
to test some fundamental questions about 
the mechanism of protein synthesis. For 
example, is the alcohol-soluble protein 
formed into residual protein by conver- 
sions at the macromolecular level, or is this 
material degraded to small molecules and 
totally reconstructed? Does glutathione 
serve merely as a sulfur-atom donor, or 
does it function as a sulf ur-peptide source ? 
Does the transport of sulfur take place in 
the sequence glutathione — alcohol-soluble 
protein — residual protein, or do the reser- 
voirs function as independent pathways? 
These questions provide a challenge to be 
faced in the coming months. 

Comparative Amino Acid Synthesis 

A vast accumulation of chemical analy- 
ses of the constituents of a wide variety of 
living organisms has led to the realization 
of striking biochemical similarities among 
all forms of life. This is particularly true 
of the proteins, which are found in all 
organisms. Furthermore, these compli- 
cated molecules are synthesized out of a 
common group of amino acid building 
blocks. 

Does the unity of the biochemical plan 



extend to the detailed pathways by which 
the amino acids are synthesized? The 
theoretical chemist could write many 
schemes by which, for instance, isoleucine 
might be synthesized. Have organisms 
tended to choose a limited number of 
specific pathways? 

A start has been made in studying this 
question. The techniques which have been 
evolved for study of synthetic pathways 
in E. coli have been successfully employed 
using the mold Neurospora crassa, the 
yeast Torulopsis atilis, and to a lesser ex- 
tent the photosynthetic organism Chlorella 
pyrenoidosa. 

Neurospora crassa 

One of the favorite objects for study of 
pathways of amino acid synthesis has been 
Neurospora crassa. By use of mutant tech- 
niques it has been possible to gather evi- 
dence regarding synthetic pathways in this 
organism. In addition, the relation be- 
tween genetic constitution and synthetic 
capacity has been studied. It was particu- 
larly important to investigate synthetic 
pathways in this organism using a differ- 
ent mode of examination, that is, radio- 
active tracers. If concordant results were 
obtained by two very different methods, 
the structure of knowledge regarding the 
pathways would be indeed secure. In our 
survey of N. crassa some ten different 
radioactive tracers have been employed, 
namely, C 14 -labeled CO*, CH3COOH, glu- 
cose, aspartic acid, glutamic acid, alanine, 
glycine, proline, ornithine, and valine. 

One of the well established synthetic 
pathways in E. coli involves aspartic acid 
as a precursor. A similar family has been 
found in N. crassa: 

Methionine 



Aspartate ^ Homoserine 



Threonine 



a keto butyrate ~^* a keto |3 methyl valerate 
~^" Isoleucine 



136 



CARNEGIE INSTITUTION OF WASHINGTON 



The pathways shown are identical with 
those found in E. colt. Earlier Neurospora 
mutant studies had indicated that methio- 
nine and threonine were derived from 
homoserine. 

A glutamic family similar to that of E. 
coli has been found : 

Glutamic acid "^Glutamic y semi aldehyde "^Proline 



Ornithine ~^" Citrulline ~^ Arginine 

Studies with Neurospora mutants had in- 
dicated a pathway from glutamic acid to 
arginine similar to that shown. The mu- 
tant evidence, however, was equivocal con- 
cerning the possible role of proline as an 
intermediate in arginine synthesis. Studies 
with labeled proline indicate that proline is 
not ordinarily on the synthetic pathway 
of arginine. A small amount of arginine 
is derived from proline, however, a fact 
which demonstrates that wild-type N. 
crassa has the capacity to utilize proline 
in arginine synthesis. The existence of 
such alternative pathways poses a problem 
of interpretation of mutant results and em- 
phasizes the desirability of determining 
pathways by more than one method. 

Synthesis of lysine in N. crassa follows 
a pathway differing from that in E. coli. 
In the mold, four of the six carbons of 
lysine are derived from the Krebs cycle. 
Considerations of specific activity show 
that the four-carbon moiety involves suc- 
cinic acid and that the additional two car- 
bons necessary for lysine are obtained from 
acetate. 

In E. coli it was found that the Krebs 
cycle is very important as a source of as- 
partic and glutamic acids. Investigations 
in this laboratory indicate a similar Krebs 
cycle in N. crassa. Earlier work had un- 
covered mutants for which such com- 
pounds as succinic acid permitted growth. 
Our work has supplied considerable addi- 
tional evidence. It has been found, in ac- 



cordance with predictions of the Krebs 
cycle, that (1) C 14 2 is used in synthesis 
of aspartic and glutamic acid; (2) the C 14 
of such glutamic acid is located in the 
carboxyl carbon; (3) in the cycle, carboxyl- 
labeled glutamic acid is decarboxylated; 
(4) CH 3 C 14 OOH is utilized in synthesis 
of glutamic acid and to a lesser extent in 
synthesis of aspartic acid; (5) aspartic acid 
can be converted into glutamic acid; (6) 
glutamic acid can be converted into as- 
partic acid. 

Another pathway of synthesis found in 
E. coli is as follows: 



Pyruvic acid 



Alanine 
^ Valine ^ Leucine 



A similar sequence has been found in N. 
crassa. A sequence involving serine is pres- 
ent in both organisms: 

^^-^T Glycine 
Serine -^^ 

^^^ Cysteine 

N. crassa and E. coli differ in their be- 
havior toward exogenous threonine. Both 
organisms use this substance in the syn- 
thesis of isoleucine. In addition, E. coli can 
degrade exogenous threonine to glycine, 
whereas N. crassa does not. 

Torulopsis utilis 

The yeast Torulopsis utilis is another 
organism which has been a favorite object 
of study. In particular, a number of in- 
vestigators have studied metabolism of iso- 
topic acetate and C0 2 . Work in this lab- 
oratory has served to confirm and extend 
this earlier work. In addition to acetate 
and CO2, some ten other labeled sub- 
stances have been used. 

Aspartic and glutamic families closely 
similar to those found in N. crassa have 
been demonstrated. The synthesis of argi- 
nine parallels that in E. coli, and our re- 
sults confirm and extend earlier observa- 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



137 



tions. Studies of lysine synthesis indicate 
that the pathway is similar to that in N. 
crassa and confirm earlier observations on 
T. utilis. 

Further evidence was found for existence 
of a Krebs cycle as in E. coli and N. crassa. 
The observations were of the same type 
as the six cited in the discussion of N. 
crassa. 

The close similarity of T. utilis and N. 
crassa extends to the two synthetic se- 
quences involving pyruvic acid and serine 
as key precursors. 

The pathways by which the sulfur amino 
acids are synthesized are not identical in 
the bacterium, yeast, and mold, though 
common features do exist. In all cases the 
carbon skeleton of cysteine is derived from 
serine, and four of the carbons of methio- 
nine originate from aspartic acid via homo- 
serine. Differences are found in the ease of 
utilization of inorganic sulfur sources and 
particularly in the metabolism of organic 
sulfur compounds. For instance, N. crassa 
and T. utilis can use methionine as a sole 
sulfur source, whereas E. coli cultures do 
not grow under such circumstances. Ex- 
ogenous cystathionine is used by the mold 
and yeast but not by E. coli. 

Information regarding cellular organi- 
zation is a by-product of isotopic competi- 
tion studies. Investigations of the aspartic 
family revealed a similar degree of compe- 
tition by aspartic acid, homoserine, threo- 
nine, a keto butyric acid, a keto (3 methyl 
valeric acid, and isoleucine in the three 
respective organisms. On the other hand, 
exogenous glutamic acid, which is an effec- 
tive competitor in E. coli, has little effect 
in N. crassa or T. utilis. Other members 
of the glutamic family compete more suc- 
cessfully in E. coli than in mold or yeast, 
although in the case of proline the differ- 
ence is less marked. It appears that in 
almost all respects the biosynthetic path- 
ways and organization of N. crassa and T. 



utilis are identical. In many ways this pair 
is similar to E. coli, though differing in a 
few respects. 

Studies of the pathways of amino acid 
synthesis in Chlorella pyrenoidosa are 
rather fragmentary. The pattern of acetate 
incorporation is strikingly similar to that 
found in N. crassa. Dark fixation of C 14 2 
gives rise to labeled aspartic and glutamic 
acids, thus making it likely that a Krebs 
cycle is operative in this organism. 

These investigations of the comparative 
biosynthetic pathways point anew to the 
existence of great similarities in the bio- 
chemical plan of living things. At the 
same time, it is also clear that differences 
in synthetic patterns exist and that some 
caution must be employed in transferring 
results from one organism to another. 

Biological Processes in Escherichia coli 

The biological syntheses observed by the 
use of isotopes, isotopic competition, and 
chromatography have been given quanti- 
tative expression in terms of the flow of 
carbon, sulfur, and phosphorus. These 
syntheses begin with relatively simple raw 
materials and yield finally an extraordi- 
nary variety of organic chemicals. Yet liv- 
ing bacteria are more than a bewildering 
collection of complex chemicals derived 
from sugar, salts, and water. They are re- 
sponsive mechanisms, reacting instantly 
and sometimes violently to subtle changes 
in their environment. They tend to resist 
change rather than undergo change, but 
do adjust when the stresses are great, and 
successfully preserve integrated activities 
in differing environments. Although these 
are qualities not always interpretable in 
exact terms, they are among the most ob- 
vious characteristics of living things. Many 
of their facets have been examined in this 
and earlier reports, and they have become 
perhaps less mysterious as a result. 



138 



CARNEGIE INSTITUTION OF WASHINGTON 



The bacteria which have been studied 
are freely permeable to most metabolites. 
Consequently, the protoplasm of the cell 
is in intimate contact with the foods in its 
environment and may be expected to re- 
spond biochemically to chemical changes 
in the nutritive medium. 

When a growing cell is presented with 
a metabolite which is particularly suitable 
for synthesis, the cell utilizes it, ordinarily 
without delay, to make the chemicals it 
needs. In most cases where the metabolite 
is one that the cell would have made and 
used if left to its own devices, no adjust- 
ment in its biochemical apparatus is found. 
The cell has not distinguished between ex- 
ogenous and endogenous chemicals. Al- 
though this behavior is not necessarily to 
be expected in such a highly integrated 
chemical system, it is the usual situation, 
and one which has made isotopic competi- 
tion an effective tool. In exploiting the in- 
ability of the cell to make this distinction, 
it has been found possible to introduce 
chemicals one at a time into the operations 
of the cell and by following their conver- 
sion learn about normal mechanisms and 
processes. The biological syntheses per- 
formed by the cell generally result in the 
formation of new protoplasm, thereby 
"bottling up" energy rather than releasing 
it through degradative processes. The 
Krebs cycle serves as a striking example of 
this property. The conversions which take 
place in this cycle and in many other cel- 
lular processes are highly specific and are 
related in precise ways to the chemical na- 
ture of the compound fed and the com- 
pounds formed. The specificity of the 
conversions which occur contrasts with the 
situation in other organisms, especially 
adult forms of higher animals, where rela- 
tively nonspecific utilization of metab- 
olites is the rule. In the bacterium the 
economy of the cell appears largely to be 
devoted to synthesis, rather than to replace- 



ment or repair. Thus, there is little ex- 
change of the constituents of protein or 
nucleic acid with components in the cul- 
ture medium, and what has been called 
the "dynamic state" has relatively little 
meaning in the biochemistry of growing 
E. coli. 

Some metabolites supplied in the culture 
medium are distinguished from similar 
materials made and used by the cell. In 
these cases the cell changes its biochemical 
activities in immediate response to the 
presence of the added material. For ex- 
ample, E. coli makes threonine and uses it 
for isoleucine synthesis as well as to con- 
struct protein. When the bacteria are sup- 
plied threonine in ordinary culture media, 
they carry out these functions with it and 
in addition convert it to glycine. The gly- 
cine so formed is used in peptide, protein, 
and nucleic acid synthesis. The bacteria 
respond to the presence of threonine by 
calling into action a "glycine-from-threo- 
nine" process. This process is not nor- 
mally operative, yet the capacity to bring 
about the conversion is present. How the 
cell keeps this capacity from being ex- 
hibited in the absence of exogenous threo- 
nine is not known. A reasonable hypothe- 
sis, however, is that bacterial threonine is 
bound into an active complex which is not 
convertible to glycine. The experiments on 
threonine, while helping to explore some 
amino acid pathways, have thus also 
yielded some insight into the chemical or- 
ganization of the cell. When such insight 
can be formulated in terms of spatial ar- 
rangements of parts and sequences of 
events, we may hope to understand how a 
living system integrates the diverse proc- 
esses which do occur, and keeps other pos- 
sible activities from occurring. 

It is a common observation that the 
kinds and amounts of chemicals which 
comprise the bacterial cell remain remark- 
ably constant in spite of radical changes in 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



139 



the environment in which the cell develops. 
Alterations in the constituents of the cell 
are in general progressively less as struc- 
tures become more highly organized. 

Chemically, the bacterial cell may be 
visualized as a series of classes of chem- 
icals, the members of the classes becoming 
increasingly larger and more complex 
along the series. Thus, in the water space 
within the cell are all the constituents pres- 
ent in the medium. They include water, 
salt, sugar, and a host of other organic 
compounds of relatively low molecular 
weight. In another class are the chemicals 
which do not permeate freely but which 
may be extracted from the cells by means 
of cold dilute acid. These include pep- 
tides, such as glutathionine, and other 
complex organic molecules. These com- 
pounds are part of the organized proto- 
plasm of the cell, but their associations 
with proteins or nucleic acid are easily 
disrupted. In still another class, the alco- 
hol-soluble chemicals, are found lipids and 
complex polypeptides. The polypeptide 
material contains the same amino acids in 
nearly the same proportions as the rest of 
the bacterial protein. Finally, there are the 
truly macromolecular components, the re- 
sidual proteins and the nucleic acids. 

The water-space components reflect 
every chemical change in the environment. 
Thus, if sodium salts in the medium are 
replaced by potassium analogues, potas- 
sium salts are found in the cell. Changes 
in the biochemical activity of the cell are 
also reflected by the water-space constitu- 
ents, and through such changes the cell 
alters the environment in which it devel- 



ops. For example, a medium containing 
glucose and homoserine supplied to grow- 
ing cells will be found to contain appre- 
ciable quantities of organic compounds de- 
rived from glucose, and specifically related 
to the metabolism of homoserine and to 
the synthesis of methionine and isoleucine. 
These compounds are not found in the 
absence of homoserine. 

The acid-soluble portion is somewhat 
less variable in relation to changes in the 
environment. Nevertheless, it will change 
whenever the stresses are large enough. 
When E. coli is starved for sulfur by re- 
moval of the supply in the medium, the 
sulfur of glutathione is utilized for the 
synthesis of protein methionine and cys- 
tine, whereas normally it does not function 
in this way. On continued sulfur starva- 
tion, even the alcohol-soluble materials are 
attacked and utilized for making residual 
protein. Finally, all protein synthesis 
ceases and growth stops. In spite of these 
extreme conditions, the residual proteins 
and nucleic acids have not undergone 
qualitative change, and their relative pro- 
portions remain constant. 

Processes which give rise to variation, 
as well as mechanisms which prevent 
change, are to be found at every level of 
the biochemical activities of the bacterial 
cell. They may be correlated with the de- 
gree of complexity of the collections of 
chemicals considered, and depend for de- 
tail on the particular activity studied. 
Whatever their specific qualities, they 
are orderly, integrated processes. They 
may be controlled, altered, and sometimes 
predicted. 



OPERATIONS AND STAFF 

Co-operative Work of the Department of the National Research Council, Na- 

The Department has pursued the Insti- tional Institutes of Health, National Bu- 

tution's policy of co-operation by engaging reau of Standards, Department of De- 

in research activities with representatives fense, Geological Survey, Geophysical In- 



140 



CARNEGIE INSTITUTION OF WASHINGTON 



stitute of Huancayo (Peru), Catholic and 
Cornell Universities, University of Alaska, 
Univeisity of Virginia, and commercial 
organizations. Close liaison has been main- 
tained with international scientific organi- 
zations such as the International Union 
of Geodesy and Geophysics and the Inter- 
national Scientific Radio Union. We have 
had visiting investigators, some on fellow- 
ship appointments, from various countries 
including Denmark, England, Holland, 
Norway, Scotland, and South Africa. 

Our joint investigations of seismic phe- 
nomena and the age of igneous intrusives 
have been continued with the Geophysical 
Laboratory. We are indebted to the Na- 
tional Bureau of Standards and the De- 
partment of the Navy and to many indi- 
vidual collaborators in this country and 
abroad for assistance in the radio astron- 
omy programs. The Department of the 
Navy has also continued to help with our 
seismic program. 

Assistance is being given to the Uni- 
versity of Western Australia in a project 
for using isotope and mass-spectrograph 
procedures for the determination of ages of 
rocks in Australia. 

Cosmic-ray meters have been continued 
in operation at widely distributed points 
through the generous co-operation of the 
observatories at Huancayo, Peru; Christ- 
church, New Zealand; Godhavn, Green- 
land; and Cheltenham, Maryland. 

Government contracts, as mentioned in 



previous reports, have been continued, 
without subsidy, for investigations of the 
earth's crust, cosmic rays, and the meas- 
urement of the ages of igneous intrusives 
and other minerals, especially in Pre- 
Cambrian rocks. One staff member did 
research work for the government for the 
entire report year, and one to July 15, 1952, 
both on full-time leave of absence; other 
staff members have acted as consultants for 
short periods. 

Administration and Operation 

We have continued to edit the Journal 
of Geophysical Research, and the Institu- 
tion has continued to meet part of the pub- 
lication expenses. 

Lectures 

G. M. Temmer gave a series of twelve 
informal lectures for the staff during De- 
cember and January on "Physics of the 
nucleus in the medium and low energy 
region." 

Lectures were given by visitors as fol- 
lows: 

September 18, 1952, "Physics at the Uni- 
versity of Zurich," Hans H. Staub. 

October 6, 1952, "Terrestrial magnet- 
ism," S. K. Runcorn. 

November 20, 1952, "Two-wavelength 
microscopy," M. J. Buerger. 

January 21, 1953, "The chemical com- 
position of the primary cosmic radiation," 
D. M. Ritson. 



BIBLIOGRAPHY 



Abelson, P. H. Amino acid sequence in pro- 
teins. (Abstract) Science, vol. 115, p. 479 
(1952). 

E. T. Bolton, and E. Aldous. Utiliza- 
tion of carbon dioxide in the synthesis of 
proteins by Escherichia coli. I. Jour. Biol. 
Chem., vol. 198, pp. 165-172 (1952). 

Utilization of carbon di- 



oxide in the synthesis of proteins by Escher- 
ichia coli. II. Jour. Biol. Chem., vol. 198, 

pp. 173-178 (1952). 
— See Bolton, E. T.; Roberts, R. B. 



Ahrens, L. H. See Aldrich, L. T.; Herzog, L. F. 
Aldous, E. See Abelson, P. H.; Bolton, E. T. 
Aldrich, L. T., J. B. Doak, and G. L. Davis. 
Mineral age measurement: Mass spectromet- 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



I 4 I 



ric determinations of Rb 87 and Sr 87 in le- 
pidolites. (Abstract) Bull. Geol. Soc. Amer., 
vol. 63, p. 1230 (1952). 

The use of ion exchange 

columns in mineral analysis for age determi- 
nation. Amer. Jour. Sci., vol. 251, pp. 377- 

387 (i953)- 

— L. F. Herzog, J. B. Doak, and G. L. 
Davis. Variations in strontium isotope abun- 
dances in minerals. Part 1: Mass spectro- 
metry: analysis of mineral sources of stron- 
tium. Trans. Amer. Geophys. Union, vol. 
34, pp. 457-460 (1953). 

W. K. Holyk, F. B. Whiting, 

and L. H. Ahrens. Variations in isotopic 
abundances of strontium. Phys. Rev., vol. 
89, pp. 631-632 (1953). 

— See Davis, G. L.; Herzog, L. F.; Nico- 



ion-exchange columns. (Abstract) Bull. 
Geol. Soc. Amer., vol. 63, p. 1242 (1952). 
— See Aldrich, L. T.; Keith, M. L. 



LAYSEN, L. O. 

Bolton, E. T., and P. H. Abelson. Utilization of 
carbon dioxide in the synthesis of protein 
and nucleic acid by Escherichia coli. (Ab- 
stract) Science, vol. 115, p. 479 (1953). 

and E. Aldous. Utilization of 

carbon dioxide in the synthesis of nucleic 
acid by Escherichia coli. Jour. Biol. Chem., 
vol. 198, pp. 179-183 (1952). 

R. Britten, and D. B. Cowie. Synthesis 

of the aspartic and glutamic families of 
amino acids by Escherichia coli. (Abstract) 
Science, vol. 117, p. 465 (1953). 

See Abelson, P. H.; Cowie, D. B.; Rob- 



erts, R. B. 
Britten, R. The scattering of 31.5-Mev protons 
from several elements. Phys. Rev., vol. 88, 
pp. 283-294 (1952). 

See Bolton, E. T. 

Brown, H. S. See Patterson, C. 

Cowie, D. B., and E. T. Bolton. Sulfur metab- 
olism in Escherichia coli. IV. Influence of 
nonmethionine sulfur compounds upon a 
methionine requiring mutant. Jour. Bac- 
teriol., vol. 64, pp. 87-96 (1952). 

N. P. Heydenburg, and G. C. Phillips. 

Inelastic scattering of protons from light 
nuclei. Phys. Rev., vol. 87, pp. 304-306 
(1952). 

See Bolton, E. T. 



Davis, G. L., and L. T. Aldrich. Determination 
of the age of lepidolites by the method of 
isotope dilution. Bull. Geol. Soc. Amer., 
vol. 64, pp. 379-380 (1953). 

Mineral age measurement: Chem- 
ical separations of Rb and Sr by means of 



Doak, J. B. See Aldrich, L. T.; Keith, M. L.; 
Nicolaysen, L. O. 

Ferraro, V. C. A. On the theory of the first 
phase of a geomagnetic storm: A new il- 
lustrative calculation based on an idealised 
(plane not cylindrical) model field distribu- 
tion. Jour. Geophys. Res., vol. 57, pp. 15- 

49 (1952). 

Forbush, S. E. See Neher, H. V. 

Graham, J. W. Changes of ferromagnetic min- 
erals and their bearing on magnetic proper- 
ties of rocks. Jour. Geophys. Res., vol. 58, 
pp. 243-260 (1953). 

(Discussion). Rev. Mod. Phys., vol. 25, 

pp. 295-296 (1953). 

Exsolution phenomena and the magnetic 

properties of rocks. (Abstract) Science, vol. 
117, p. 3044 (1953). 

Note on the significance of inverse mag- 



netizations of rocks. (Letter to editor) Jour. 
Geophys. Res., vol. 57, pp. 429-431 (1952). 
Herzog, L. F., L. T. Aldrich, W. K. Holyk, 
F. B. Whiting, and L. H. Ahrens. Varia- 
tions in strontium isotope abundances in 
minerals. Part 2: Radiogenic Sr 87 in biotite, 
feldspar, and celestite. Trans. Amer. Geo- 
phys. Union, vol. 34, pp. 461-470 (1953). 

See Aldrich, L. T. 

Heydenburg, N. P., and G. M. Temmer. Alpha- 
particle scattering in nitrogen. Phys. Rev., 
vol. 91, p. 439 (1953). 

See Cowie, D. B.; Rose, W. B.; Talbott, 

F. L.; Temmer, G. M. 

Holyk, W. K. See Aldrich, L. T.; Herzog, L. F. 

Hudspeth, E. L. See Rose, W. B. 

Inghram, M. G. See Patterson, C; Tilton, 

G. R. 

Keith, M. L., M. A. Tuve, G. L. Davis, and J. B. 
Doak. Ratio of oxygen isotopes in quartz 
of contrasted origin. (Abstract) Bull. Geol. 
Soc. Amer., vol. 63, p. 1270 (1952). 

Larsen, E. S. See Patterson, C. 

Neher, H. V., and S. E. Forbush. Correlation of 
cosmic-ray ionization measurements at high 
altitudes, at sea level, and neutron intensi- 
ties at mountain tops. Phys. Rev., vol. 87, 
pp. 889-890 (1952). 

Nicolaysen, L. O., L. T. Aldrich, and J. B. 
Doak. Age measurements on African micas 
by the strontium-rubidium method. (Ab- 
stract) Trans. Amer. Geophys. Union, vol. 
34, p. 342 (1953). 



142 



CARNEGIE INSTITUTION OF WASHINGTON 



Parkinson, W. C. Note on the concentration of 
condensation nuclei over the western At- 
lantic. (Letter to editor) Jour. Geophys. 
Res., vol. 57, pp. 314-315 (*95 2 )- 

Patterson, C., H. S. Brown, M. G. Inghram, 
E. S. Larsen, and G. R. Tilton. The dis- 
tribution of lead and uranium in a precam- 
brian granite. (Abstract) Trans. Amer. Geo- 
phys. Union, vol. 34, p. 343 (1953). 

See Tilton, G. R. 

Phillips, G. C. See Cowie, D. B. 

Roberts, R. B., and P. H. Abelson. The role of 
the tricarboxylic acid cycle in amino acid 
synthesis in Escherichia coli. (Abstract) Sci- 
ence, vol. 117, p. 471 (1953). 

and E. T. Bolton. The role of gluta- 
thione in protein synthesis by Escherichia 
coli. (Abstract) Science, vol. 115, p. 479 
(1952). 

Rose, W. B., E. L. Hudspeth, and N. P. Heyden- 
burg. Neutrons from deuteron bombard- 
ment of N 14 . Phys. Rev., vol. 87, pp. 382- 
383 (1952). 

Scott, W. E. List of recent publications. Jour. 
Geophys. Res., vol. 57, pp. 318-322 (1952); 
vol. 57, pp. 435-438 (1952); vol. 57, pp. 
543-546 (1952); vol. 58, pp. 121-126 (1953); 
vol. 58, pp. 291-294 (1953). 

Talbott, F. L., and N. P. Heydenburg. Gamma- 
ray resonances in the alpha-particle bom- 
bardment of beryllium and boron. Phys. 
Rev., vol. 90, pp. 186-187 (1953). 



Temmer, G. M., and N. P. Heydenburg. Preci- 
sion alpha-alpha scattering at low energies. 
II. Phys. Rev., vol. 90, p. 340 (1953). 

See Heydenburg, N. P. 

Tilton, G. R., C. Patterson, and M. G. In- 
ghram. Mass spectrometric determination of 
thorium. (Abstract) Bull. Geol. Soc. Amer., 
vol. 63, p. 1305 (1952). 

See Patterson, C. 

Tuve, M. A. See Keith, M. L. 

Vestine, E. H. On variations of the geomag- 
netic field, fluid motions, and the rate of 
the earth's rotation. Proc. Nat. Acad. Sci., 
vol. 38, pp. 1030-1038 (1952). 

On variations of the geomagnetic field, 

fluid motions, and the rate of the earth's 
rotation. Jour. Geophys. Res., vol. 58, pp. 
127-145 (1953). 

Wells, H. W. F-region effects of solar eclipse 
at sunrise, Sept. 1, 1951. (Abstract) Trans. 
I. R. E., Prof. Group on Antennas and 
Propagation, No. 3, p. 210 (1952). 

Ionospheric effects of solar eclipse at sun- 
rise, Sept. 1, 195 1. Jour. Geophys. Res., vol. 
57, pp. 291-304 (i95 2 )- 

Radio interferometer technique applied 



to measurement of meteor velocities. (Let- 
ter to editor) Jour. Geophys. Res., vol. 58, 
pp. 284-286 (1953). 
Whiting, F. B. See Aldrich, L. T.; Herzog, 
L. F. 



STAFF AND ORGANIZATION 



Scientific Staff 

Director: M. A. Tuve. 
Staff Members 

Geophysics: L. T. Aldrich, S. E. Forbush, 
J. W. Graham, E. A. Johnson,* H. E. Tatel, 
G. R. Tilton, E. H. Vestine, H. W. Wells. 
Laboratory and Biophysics: P. H. Abelson, 
E. T. Bolton, R. J. Britten, D. B. Cowie, 
N. P. Heydenburg, R. B. Roberts, G. M. 
Temmer. 
Guests, Associates, Fellows, and Visiting Investi- 
gators: S. Berko, University of Virginia; H. G. 
Booker, Cornell University; J. G. Brennan, 
Catholic University; Miss B. W. Catlin, Mar- 
quette University School of Medicine; H. R. 
Crane, University of Michigan; Mrs. Josephine 
K. Doherty, National Institutes of Health; 
W. R. Duryee, National Institutes of Health; 

* On leave of absence for government work. 



C. T. Elvey, University of Alaska; G. Field, 
Princeton University; J. W. Findlay, Cavendish 
Laboratory, Cambridge, England; Miss J. Gil- 
lespie, National Institutes of Health; P. J. 
Hart, Harvard University; F. Hereford, Uni- 
versity of Virginia; H. W. Koch, National 
Bureau of Standards; B. Kok, Agricultural Col- 
lege, Holland; C. Levinthal, University of 
Michigan; Soren Lovtrup, Carlsberg Labora- 
tory, Copenhagen, Denmark; C. J. Marhoefer, 
Catholic University; Kenneth McQuillen, Uni- 
versity of Cambridge, Cambridge, England; 
Leif Owren, Institute of Theoretical Astro- 
physics, Oslo, Norway; Leon T. Parker, De- 
partment of the Navy; A. T. Price, Royal 
Technical College, Glasgow, Scotland; J. A. 
Ratcliffe, Cavendish Laboratory, Cambridge, 
England; D. M. Ritson, University of Roch- 
ester; Mrs. I. Z. Roberts; S. K. Runcorn, Uni- 
versity of Cambridge, Cambridge, England; 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



143 



Martin Ryle, Cavendish Laboratory, Cam- 
bridge, England; F. G. Smith, Cavendish Lab- 
oratory, Cambridge, England; H. H. Staub, 
University of Zurich, Switzerland; M. Sugiura, 
University of Alaska; F. L. Talbott, Catholic 
University; G. M. Temmer, National Bureau 
of Standards; R. E. Trumble, Jr., Catholic 
University; H. C. van de Hulst, Leiden Ob- 
servatory, Holland; H. J. Vogel, Yale Uni- 
versity. 

Operating Staff 

Administrative: M. B. Smith, W. F. Steiner. 

Office and Clerical: Miss I. Debber,t W. N. 
Dove, Miss E. F. French, W. C. Hendrix, 
D. J. O'Rourke, Miss H. E. Russell, Mrs. F. B. 
Silberstein, L. Tupler,J Mrs. E. A. Walck.t 

X Resigned. 



Instrument Shop: B. J. Haase, L. A. Horton, 
J. G. Lorz. 

Research Assistants and Laboratory Assistants: 
S. J. Buynitzky, H. E. Cronin, J. B. Doak, 
E. T. Ecklund, R. E. Hewitt, P. A. Johnson, 
C. J. Ksanda, Mrs. J. G. Lappin, C. A. 
Little, Jr., Mrs. E. A. MacKenzie, M. H. 
MacKenzie, P. F. Michelsen,t Miss B. K. 
Phillips, R. W. Reuschlein, W. E. Scott. 

Computer: Miss I. Lange. 

Maintenance: C. Balsam, C. R. Domton, C. P. 
Giffin, M. O. Pedersen, E. Quade, S. Swant- 
kowski. 

Part-time and Temporary Employees: Seventeen 
part-time and temporary employees were en- 
gaged during the year, usually for short pe- 
riods, to assist in the office and laboratory 
work. 



DEPARTMENT OF PLANT BIOLOGY 

St an j or d, California 
C. STACY FRENCH, Director 



It has long been known that chlorophyll 
is the principal absorber of sunlight as it 
falls on the green leaves of plants. There 
are also present in all plants other pig- 
ments, such as carotenoids and the phyco- 
bilins of various algae, which play a part 
in the photosynthetic process. It appears 
highly probable, however, that the function 
of these accessory pigments is merely that 
of light absorbers and that all they do with 
the energy which they take up is to pass 
it along to chlorophyll; that is, that they 
act solely by supplementing the light-ab- 
sorbing role of chlorophyll. A chlorophyll 
molecule, after absorbing light or receiving 
it by transfer from other pigments, has 
more energy than before, and in some way, 
probably by means of enzyme systems, 
this energy is handed on to water mole- 
cules. The result is a splitting of water to 
free oxygen and active hydrogen that can 
be used, through enzymatic chains, to re- 
duce carbon dioxide. This is the vital 
process by which green plants convert the 
energy of sunlight to usable chemical 
energy. Just how chlorophyll and the un- 
known components of this system work to- 
gether in this remarkable chain of events 
is only partly understood. 

Several of the great schools of organic 
chemistry have studied the chemical struc- 
ture of chlorophyll with the hope of elu- 
cidating its function in photosynthesis. 
This structure has been established, but 
the means by which chlorophyll acts re- 
mains unknown. Another approach to the 
problem is the study of the photochemical 
reactions of chlorophyll when dissolved in 
organic solvents. Such studies are actively 
progressing in a number of laboratories 



and have resulted in much information 
about the chemical changes caused in other 
substances by light absorbed by chloro- 
phyll. The changes that chlorophyll itself 
undergoes during these transformations are 
of particular interest in relation to the 
problem of the mechanism by which it 
acts in photosynthesis. Reversible changes 
in its absorption spectrum caused by light 
absorption, or by changes in its oxidation 
state, show that it does more than merely 
absorb light and pass on the energy. 
Chlorophyll itself, at least in reactions car- 
ried out in organic solvents, actually goes 
through reversible chemical changes much 
as do the coenzymes that carry on other 
metabolic reactions in living cells. 

Extracted chlorophyll in organic solvents 
behaves very differently from chlorophyll 
in its natural state in chloroplasts. A great 
deal of work has gone into the detailed 
study of this difference without as yet mak- 
ing entirely clear the chemical nature of 
the chlorophyll complex in the form in 
which it does its work. It has long been 
hoped that reversible changes in the ab- 
sorption spectrum of chlorophyll could be 
found in live plants, thus making it pos- 
sible to measure directly some chemical 
change in native chlorophyll as it carries 
out photosynthesis and as it is influenced 
by environmental conditions. 

Such an effect has been discovered dur- 
ing the past year, not yet in green plants, 
however, but in the purple bacteria, which 
have a somewhat different kind of chloro- 
phyll. The decrease of the main absorption 
peak and the shift of a minor peak of bac- 
teriochlorophyll in living bacteria when 
illuminated were found by Dr. L. N. M. 



M5 



146 



CARNEGIE INSTITUTION OF WASHINGTON 



Duysens, of the Biophysical Research 
Group at the University of Utrecht. Dr. 
Duysens is continuing the study of this 
phenomenon as a Research Fellow in this 
Department. He has recently found that 
the change in absorption is much greater 
when oxygen is added to the cell suspen- 
sion. The effect is also observed in water 
suspensions of disintegrated bacteria in the 
presence of an oxidant, and the effect is 
abolished by addition of a reductant. Ap- 
paratus has been devised for the study of 
the time course of this change, which ap- 
pears within a second after illumination 
and disappears within a second after the 
light is off. The further exploration of 
this effect should lead to a much clearer 
understanding of the means by which 
chlorophyll participates in photosynthesis. 
Dr. Smith's studies on the rapid forma- 
tion of chlorophyll from protochlorophyll 
when dark-grown plants are exposed to 
light have clarified a previously puzzling 
situation. Some years ago the action spec- 
trum for the transformation of proto- 
chlorophyll to chlorophyll showed that 
protochlorophyll has its absorption peak at 
650 mu in live etiolated corn leaves. It 
was found, however, that a maximum in 
the fluorescence spectrum of protochloro- 
phyll in etiolated leaves came at about 
638 mjj rather than at slightly over 650, as 
would be expected. Recent experiments 
have shown a slow change from a 650- to 
a 635-mM absorption peak in glycerine ex- 
tracts of etiolated leaves. This change takes 
place at room temperature, but not at o° C, 
in a few hours. Since the fluorescence 
measurements had necessarily been made 
with leaves inactivated by heating, the ap- 
parent discrepancy is now believed to have 
been due to the change from the native 
form of protochlorophyll to the altered 
form having the 635-mM band. In collabo- 
ration with Dr. Robert Hill it was found 
that some seed coats of squash showed 



fluorescence spectra of only the normal 
form of protochlorophyll, whereas others 
had both the normal and the altered form. 
It is not yet certain whether the altered 
form can be transformed to chlorophyll 
when illuminated. The altered form may 
simply be protochlorophyll that has been 
split off from its normal protein carrier 
so that it no longer exists as part of the 
holochrome complex. The time course of 
the protochlorophyll-to-chlorophyll trans- 
formation follows with high precision the 
rate equation for a bimolecular reaction 
when both reactants are present in equal 
concentrations, but there is so far no very 
clear understanding of the reason for this 
situation. Measurements of the rate of pro- 
tochlorophyll transformation have been 
made over the whole range from —195° 
to + 55 ° C. The fact that the process takes 
place reasonably rapidly far below the 
freezing point of water shows that it must 
go through very few if any enzyme-cata- 
lyzed steps. The optimum temperature for 
this transformation lies near 39° C. Above 
this temperature the reaction is heat-inac- 
tivated according to a pattern resembling 
the heat denaturation of proteins. Water 
suspensions of disintegrated bean leaves 
will still transform their protochlorophyll 
to chlorophyll, but barley leaves must be 
disintegrated in glycerine or in concen- 
trated sucrose solutions rather than in 
water to retain this activity. 

Light has many effects on plants in addi- 
tion to supplying the driving power for 
photosynthesis; it is used for chlorophyll 
formation, for determining the orientation 
of the parts of plants above ground, and 
for controlling the size and shape of the 
various parts of plants, besides influencing 
the ability of plants to produce flowers 
and of seeds to germinate. Another effect 
of light is to cause a change in the con- 
sistency of the material inside plant cells. 
Different colors of light have very diverse 



DEPARTMENT OF PLANT BIOLOGY 



147 



effects on these different reactions, which 
means that the absorbing pigments in- 
volved in the reactions are not all the same. 
The very small concentration of some of 
the very active pigments in the plant cells 
makes it difficult and often impossible to 
isolate and identify them. The quantitative 
effect of any particular color of light is, 
however, except for internal screening 
effects of other pigments, proportional to 
the absorbing capacity of the pigment for 
that particular wave length. Thus by meas- 
uring the response produced by many dif- 
ferent wave lengths it is possible to deduce 
the absorption spectrum and hence at least 
partially to identify the active pigments 
causing the various reactions of plants to 
light. Experiments in progress by Dr. 
Hemming I. Virgin show that only blue 
and blue-green light cause the change in 
the viscosity of cytoplasm discovered some 
years ago in water plants and recently 
found in land plants as well. There are 
difficulties in the precise measurement of 
this effect that have so far made the exact 
shape of the action spectrum hard to deter- 
mine, but the results obtained show that 
the pigment responsible is very likely a 
carotene or a riboflavin type of compound 
such as is also found to be active in the 
phototropic orientation of plants. The 
mechanism of the change of consistency 
has been shown to involve three separate 
steps: a photochemical reaction, followed 
by a slower reaction independent of light, 
and a still slower back reaction which 
diminishes the effect over a period of sev- 
eral minutes. The latter reaction is slowed 
by lowering the temperature. Though this 
change in viscosity seems to be of general 
occurrence, its physiological value, if any, 
is not known. It is certainly reasonable to 
suppose that the large changes of proto- 
plasmic viscosity induced by light in 
plant cells could drastically alter the rate 



and perhaps the nature of their metabolic 
processes. 

Much has been written about the pos- 
sible use of Chlorella as human food, but 
very little Chlorella has actually been eaten. 
Some experiments on the addition of 
Chlorella ellipsoidea, produced in Japan, 
to soups, breads, jelly rolls, noodles, and 
ice cream were made by Professor and 
Mrs. Hiroshi Tamiya. The foods were 
prepared in batches containing different 
amounts of Chlorella and as controls with- 
out any. Generally the foods were im- 
proved in taste by Chlorella, and particu- 
larly the enriched breads and ice cream 
were highly palatable to Japanese, Ameri- 
can, and European subjects. Thus the 
direct addition of Chlorella to food seems 
feasible and could add significant amounts 
of protein without unpleasant tastes. 

A study of the growth rate of Chlorella 
in intermittent light such as might be ob- 
tained in turbulent cultures has been com- 
pleted this year by Professor Jack Myers 
and Dr. J. Neal Phillips at the University 
of Texas. The program at Texas for the 
selection from nature of algal strains par- 
ticularly suitable for use in mass culture 
has been intensified and expanded to in- 
clude a search for nitrogen-fixing blue- 
green algae as well as for Chlorella strains 
having a high temperature tolerance and a 
high efficiency in bright light. One of the 
high-temperature strains is being tried in 
Professor Tamiya's pilot plant in Tokyo. 

The range-grass program carried on in 
co-operation with the U. S. Soil Conserva- 
tion Service has reached the stage where 
the new methods of interspecific hybrid 
formation and the stabilization of non- 
sexual new strains have been thoroughly 
established as a useful addition to the 
standard methods of plant breeders. This 
program has resulted in the production of 
numerous hybrids that give promise of 
having practical value as cattle forage, par- 



148 



CARNEGIE INSTITUTION OF WASHINGTON 



ticularly under the western range condi- 
tions for which they were selected. During 
the past year tests of the thirty selected 
strains previously reported have been con- 
tinued and expanded. In addition, some 
new combinations of the selected hybrids 
have been found to show characteristics 
that greatly encourage further efforts to 
test adequately their comparative value as 
forage crops. 

The planning, execution, and evaluation 
of the large-scale field tests essential for in- 
troducing the new grasses into agricultural 
use is clearly a project of great size, requir- 
ing specialized facilities. We are planning 
arrangements for further collaboration in 
testing as thoroughly as possible various 
environments for growing the new grasses 
and different ways of using them. There 
are several agencies more specifically 
adapted than the Institution to take the 
primary responsibility for such a program. 
As the results of the proposed collaborative 
tests become available, some agency other 
than the Institution may desire to assume 
complete responsibility for expediting their 
practical evaluation and for introducing 
the new grasses into commercial use. 



Chromosome counts of numerous indi- 
viduals of seven of the more interesting 
double and quadruple Poa hybrids have 
thrown further light on the mechanism of 
inheritance in the apomictic grasses. 

The genetics, cytology, and ecology of 
the various races of single species which 
are adapted to different climates have long 
been of interest to the Department. New 
hybrids are being made of various climatic 
races of Mimulus, a group especially favor- 
able for the analysis of the factors that 
determine the fitness of different ecological 
races to the climates for which they are 
specifically adapted. 

Studies by Drs. Ralph W. Chaney and 
R. N. Lakhanpal of two fossil floras from 
Oregon show that there were local differ- 
ences in vegetation during the Oligocene 
epoch similar to the differences existing 
today on opposite sides of the Cascade 
Range. It has become apparent that some 
floral differences must be explained on the 
basis of environmental dissimilarities rather 
than of discrepancies in age, in order to 
avoid errors in the dating of fossil-bearing 
beds. 



PERSONNEL 



Biochemical Investigations 



Staff: C. Stacy French, Director, Harold W. 

Milner, James H. C. Smith, Herman A. 

Spoehr, Chairman Emeritus, Violet K. 

Young. 
Visiting Investigators: Robert Hill, Jack 

Myers, Hiroshi Tamiya, Hemming I. 

Virgin. 
Research Fellows: L. N. M. Duysens, Bessel 

Kok, Robert W. Krauss. 
Research Assistants: Allen Benitez, Edwin A. 

Davis. 
Technical Assistants: Richard M. Cook, Wal- 
ter W. Holt, Elwin W. Seeley. 



Experimental Taxonomy 



Staff: Jens C. Clausen, Paul Grun, William 

M. Hiesey. 
Guest Investigator: Friedrich Ehrendorfer. 
Stanford University graduate student associ- 
ated with the Department: George H. 

Ward. 
Research Assistants: Charles T. Mason, Jr., 

Malcolm A. Nobs. 
Technical Assistants: Robert W. Ayres, 

Arthur L. Hawk, Edwin H. Ketchledge, 

Edward L. Triplett. 
Clerical Assistants: Marion S. Bracken, John 

M. Bracken. 
Gardener: Wesley B. Justice. 



DEPARTMENT OF PLANT BIOLOGY 



I 49 



Research Associate 

Ralph W. Chaney, Professor of Paleontology, 
University of California, Berkeley. 

Department Secretary 
Wilbur A. Pestell. 

Mechanical Engineer 
Louis R. Kruger. 

Custodians 
Donald B. Muir, Richard P. Ludolph, Jr. 

Dr. Paul Grun has been at the Karo 
linska Institute, Stockholm, Sweden, since 
September 1952, investigating the ultra- 
violet absorption spectra of isolated root- 
tip nuclei. 

Professor Hiroshi Tamiya, Director of 
Tokugawa Institute and Professor of Biol- 
ogy of Tokyo University, was a guest of the 
Department for several months while in 
this country on a grant from the National 



Research Council. During this time he 
wrote two chapters for the Institution's 
monograph Algal Culture: From Labo- 
ratory to Pilot Plant and, with Mrs. Ta- 
miya, prepared various foods containing 
Chlorella which were evaluated for palata- 
bility by the staff and by various visitors. 

We were also fortunate this year to have 
a visit of several weeks from Dr. Robert 
Hill, of Cambridge University. This visit 
provided a stimulating opportunity for 
collaboration on several aspects of the 
problem of the state of chloroplast pig- 
ments in living cells, the results of which 
are reported below under "The absorption 
and fluorescence spectra of natural pro- 
tochlorophyll." 

Dr. Glenn W. Todd, of the California 
Institute of Technology, visited the Depart- 
ment for a week to measure the fluores- 
cence spectra of the pigments of certain 
light-sensitive seeds. 



BIOCHEMICAL INVESTIGATIONS 



The Protochlorophyll-Chlorophyll 

Transformation : The Nature of 

Protochlorophyll in Leaves 

James H. C. Smith and Allen Benitez 

The driving power of photosynthesis is 
the light captured by chlorophyll. How 
chlorophyll passes on this captured energy 
to other parts of the photosynthetic system 
has been the subject of a great deal of re- 
search and speculation. Most of the earlier 
conceptions of this transfer represented it 
as a reversible chemical change involving 
the pigment itself, but the more recent in- 
terpretations have tended more and more 
to ascribe it to physical phenomena. These 
physical interpretations assume that the 
pigment molecule undergoes no chemical 
change, but because of its excited state in- 
duces chemical change in other parts of 
the photosynthetic system. 



A factor that has contributed to lack of 
clarity in regard to this energy transfer is 
ignorance concerning the condition of 
chlorophyll in the plant. Spectroscopic 
examination has shown that chlorophyll 
when in the plant exists in a different state 
from that found when it is dissolved in 
organic solvents. Until the reason for this 
difference is clarified, it may be difficult to 
ascertain whether the energy transfer in 
photosynthesis is accomplished by chemical 
or by physical means. 

If chlorophyll in its natural state is 
bound to a carrier, the resulting complex 
can be considered to be a compound — pre- 
viously named chlorophyll holochrome — 
in which reversible chemical transforma- 
tions could take place in the carrier portion 
without causing a detectable change in the 
pigment portion. 

Various attempts have been made to iso- 



150 



CARNEGIE INSTITUTION OF WASHINGTON 



late and determine the chemical nature of 
the chlorophyll holochrome, but the re- 
sults have been ambiguous. Much of the 
ambiguity has come from inability to test 
the isolated holochrome for unimpaired 
function. 

It seems likely that one approach to an 
understanding of the nature of the chloro- 
phyll holochrome is through an under- 
standing of the protochlorophyll holo- 
chrome. In the transformation of proto- 
chlorophyll to chlorophyll, the chemical 
change is small. Since the transformation 
is so readily effected, it is assumed that the 
change in the carrier portion of the holo- 
chrome is also small. If, therefore, the 
constitution of the protochlorophyll holo- 
chrome could be determined, our knowl- 
edge of the chlorophyll holochrome should 
be greatly increased. 

With this in mind, the objective of this 
year's work has been to determine the na- 
ture of the protochlorophyll holochrome by 
examining the effects of various external 
factors on the protochlorophyll-chlorophyll 
transformation within the leaf, and by iso- 
lating this holochrome in a state in which 
it can be transformed. If the isolated holo- 
chrome is active in respect to this trans- 
formation, it may also show activity in 
other respects related to photosynthesis. 

Effect of temperature. The effect of tem- 
perature on the protochlorophyll-chloro- 
phyll transformation in the range from 
+ 55.3 to -195° C was studied in detail. 

When dark-grown barley leaves were 
maintained at 39° C and above, they lost 
their ability to carry out the transforma- 
tion. The higher the temperature, the 
more quickly they lost this ability. At 
39° C the loss was barely perceptible after 
an hour, whereas at 55.3° C it was 96 per 
cent complete in 5 minutes. The capacity 
for transformation was not lost on account 
of destruction of the pigment portion of 
the holochrome, since the unaltered pig- 



ment could be extracted after the tempera- 
ture treatment, but it was lost in all like- 
lihood because of the effect of temperature 
on the carrier. The pattern of behavior at 
temperatures between 39° and 55° C 
strongly suggests that the protochlorophyll 
holochrome is a pigment-protein complex. 

The extent of transformation of proto- 
chlorophyll into chlorophyll for a definite 
amount of radiation was measured at 
several temperatures from room tempera- 
ture to liquid-nitrogen temperature. As the 
temperature was decreased, the percentage 
transformation was decreased. The trans- 
formation was 90 per cent at 23 ° C, 72 per 
cent at — 20 °C, 36 per cent at —77° C, and 
zero at —195° C. It is remarkable that 
this biochemical transformation proceeds 
to so great an extent at such a low tempera- 
ture as —77° C. This provides evidence 
against enzymatic control of the trans- 
formation, because those enzyme systems 
which have been studied at low tempera- 
tures have shown no activity at —77° C, 
and only slight activity at —20° C. 

Freezing of the leaves at — io° and 
— 20° C did greater damage to the trans- 
formation system than was consistent with 
the over-all trend of transformation with 
temperature. Damage to biological sys- 
tems by slow freezing is common, and 
undoubtedly the damage to the protochlo- 
rophyll holochrome can be ascribed to the 
same cause. This interpretation is sub- 
stantiated by the observation that leaves 
frozen at much lower temperatures and 
then brought to — 10 ° or —20° C some 
time before being illuminated transformed 
a greater percentage of their protochloro- 
phyll than did leaves which had been ex- 
posed at —io° or —20° C only. 

Even when the illumination periods 
were long, the transformation never 
reached completion, but approached a lim- 
iting value. This value was less, the lower 
the temperature. At 20° C the limit of the 



DEPARTMENT OF PLANT BIOLOGY 



151 



conversion of the protochlorophyll con- The fact that the reaction velocity agrees 
tained in the leaves was 95 per cent; at with the second-order rate law and is pro- 
— 40° C, 71 per cent; and at —70° C, 58 portional to the intensity of the radiation 
per cent. This effect of temperature was suggests that the transformation is pro- 
reversible; that is, leaves which had been duced either by the interaction of two 
treated at a very low temperature in the protochlorophyll molecules, one of which 
dark, when brought to a higher tempera- has been photoactivated, or by interaction 
ture and illuminated, transformed the of a protochlorophyll molecule with a sub- 
same percentage of their protochlorophyll stance formed by light absorbed in another 
as if they had been treated at the higher protochlorophyll molecule, 
temperature only. This was true so long The rate constant of this second-order 
as the higher temperature was below the reaction was directly proportional to the 
thawing point. If, however, the leaves light intensity and varied with the temper- 
were first illuminated at the lower temper- ature. The values of the rate constant 
ature and then at the higher temperature, ( X io 5 ) found at the various temperatures 
the reversibility was only partial. In this were: 13.2 at 20° C, 7.4 at —40° C, and 
case, the percentage transformation was 1.4 at —70° C. (The wave length of the 
slightly below that obtained at the higher incident light used for these measurements 
temperature, but it was considerably above was 579/577 mu.) The temperature coefn- 
that obtained at the lower temperature, cient of the rate constant was what would 
Thus it appears that illumination of the be expected for a photochemical reaction 
holochrome, besides bringing about trans- that derived its activation energy almost 
formation of protochlorophyll to chloro- exclusively from the light absorbed, 
phyll, destroys to some extent the capacity These facts imply that native protochlo- 
of the holochrome for transformation. rophyll is a pigment-protein complex whose 

The progress of the transformation was phototransformation requires in some way 

measured as a function of the amount of interaction between two protochlorophyll 

radiation incident on the leaves. At molecules. 

6° ±2° C, these measurements were made Attempted isolation of the holochrome. 

at wave lengths 589, 579/577, 546, and 436 The second means used to determine the 

mu. At the three longest wave lengths, the nature of native protochlorophyll was the 

rate of the transformation was proportional isolation of the holochrome. In Year Book 

to the square of the protochlorophyll con- No. 51 (1951-1952) it was reported that 

centration, this second-order rate law be- etiolated leaves which had been disinte- 

ing followed very closely. At 436 mu, grated by grinding in glycerine trans- 

however, this law was not strictly obeyed, formed a large percentage of their proto- 

The cause of the difference between the chlorophyll to chlorophyll when the brei 

reaction at 436 mu and that at the other was illuminated. During the past year, 

wave lengths is unknown. glycerine suspensions of ground dark- 

If this were a strictly photochemical re- grown barley leaves have been obtained 

action, in which one protochlorophyll mol- which had interesting properties. To pre- 

ecule acted as the absorber of the activating pare the suspensions, the leaves were 

light and also as the reactant, the conver- ground in glycerine and the liquid 

sion would have progressed in proportion squeezed through a finely woven cloth, 

to the amount of protochlorophyll present, The suspensions were freed of the largest 

that is, according to the first-order rate law. particles by high-speed centrifugation. 



152 



CARNEGIE INSTITUTION OF WASHINGTON 



Transparent, opalescent suspensions were mu. The dissimilarity in absorption by 

obtained by this treatment. the chlorophyll holochromes — one newly 

Such a suspension was found to contain formed from protochlorophyll holochrome, 

an absorption band at 650 mu. When this the other from green leaves — suggests that 

suspension was allowed to stand in the the state of native chlorophyll changes 

dark at room temperature, the position of during its development and accumulation, 

the absorption band shifted to 635 mu. A comparable observation has been made 

The shift in position of the band was much by Krasnovskii. 

slower at 6° C than at room temperature. Whole leaves, when frozen and thawed, 

These facts have an important bearing on lose their capacity for photochemically 

previous observations: The action spec- transforming protochlorophyll to chloro- 

trum for the conversion of protochloro- phyll. The protochlorophyll holochrome in 

phyll to chlorophyll in corn leaves had its glycerine suspension, however, after being 

long-wave-length maximum at 650 mu, but kept for 3 hours at the temperature of solid 

the fluorescence spectrum of dark-grown carbon dioxide and then brought to room 

leaves had a maximum at 638 mu. These temperature, still retained this ability. This 

two values were discrepant, since the fluo- is an interesting illustration of glycerine's 

rescence band should have been at longer efficacy in preserving physiological activity 

wave lengths than the corresponding ab- in biological material at low temperature, 

sorption band. This discrepancy raised This effect may be useful in future work 

troublesome questions concerning the in- on the isolation of the holochrome. 
terpretation of the action-spectrum data. Etiolated leaves when ground with 62.5 

But discovery that a freshly prepared glyc- per cent sucrose solutions also form sus- 

erine extract of dark-grown leaves had a pensions which maintain the capacity of 

maximum at 650 mu, identical in position protochlorophyll holochrome for photo- 

with the action-spectrum maximum, and transformation to chlorophyll holochrome. 

that this band shifted spontaneously to By expelling the strained and centrifuged 

635 mu, a position consistent with the suspensions through a small orifice under 

fluorescence band at 638 mu, gave a plausi- high pressure (see Milner et ah, Year Book 

ble explanation for the discrepancy pre- No. 48, 1948-1949, p. 88) the particles 

viously encountered. were reduced to very small size. Some 

When the glycerine suspension was ir- particles, however, were still microscopi- 

radiated, the protochlorophyll holochrome cally detectable with dark-field illumina- 

absorption band at 650 mu decreased and tion. Whether these small particles were 

a new absorption band with wave-length the seat of the transformation is yet to be 

maximum at about 670 to 675 mu ap- determined. 

peared. This new band was ascribable to The destruction of the protochlorophyll 
the chlorophyll a holochrome. These facts holochrome, during the isolation process, 
demonstrated that the protochlorophyll occurs more readily in some leaves than in 
holochrome could be separated from the others: in etiolated barley leaves the de- 
leaf in active form by the procedure de- struction is very rapid, whereas in etiolated 
scribed. bean leaves it is relatively slow. Dark- 
It should be noted that the position of grown barley leaves, ground with dilute 
the absorption band of the chlorophyll salt solutions, lose nearly all their proto- 
holochrome obtained from green leaves chlorophyll and fail completely to trans- 
by grinding with glycerine was at 678 form what remains; etiolated bean leaves, 



DEPARTMENT OF PLANT BIOLOGY 



153 



treated similarly, retain protochlorophyll 
and the power to transform it. 

Although a suspension of the proto- 
chlorophyll holochrome can be obtained 
from bean leaves by grinding with dilute 
salt solutions alone, suspensions more satis- 
factory in respect to stability, retention of 
pigment, and power of transformation can 
be obtained by grinding with glycerine or 
concentrated sucrose solution. The position 
of the bean protochlorophyll-holochrome 
absorption maximum lies at 635 to 640 mu. 
This position differs from that found for 
the freshly prepared glycerine suspensions 
of barley-leaf protochlorophyll holochrome, 
650 mu, but agrees with that of prepara- 
tions which have been permitted to stand 
for some time at room temperature in the 
dark. The significance of these observa- 
tions is not yet clear, but it may be that 
different protochlorophyll holochromes 
exist. 

Many experiments have been performed 
to isolate the active protochlorophyll holo- 
chrome from suspensions of it in salt solu- 
tions, glycerine, and concentrated sucrose 
solutions. As yet no real success has been 
attained. The results obtained so far point 
to the holochrome's being particulate, and 
experiments are being planned to test this 
assumption. 

The Absorption and Fluorescence 
Spectra of Natural Proto- 
chlorophyll 

Robert Hill, James H. C. Smith, and 
C. S. French 

The action spectrum for the transforma- 
tion of protochlorophyll to chlorophyll was 
determined several years ago (see Smith, 
Koski, and French, Year Book No. 48, 
1948-1949, p. 91). When this action spec- 
trum was compared with the absorption 
spectrum of protochlorophyll dissolved in 
organic solvents, there was little room for 



doubt that in the transformation proto- 
chlorophyll was the light-absorbing agent 
as well as the reactant. But discrepancies 
existed: the positions of the action-spec- 
trum bands were displaced from those of 
the absorption bands of protochlorophyll 
in organic solvents; and the shape of the 
action-spectrum curve differed from the 
shape of the absorption-spectrum curve of 
protochlorophyll. These differences would 
exist if the absorption spectrum of native 
protochlorophyll were displaced from that 
of the extracted pigment as is the case with 
other plant pigments. More convincing 
evidence than this assumption, however, 
would be a demonstration that the absorp- 
tion bands of natural protochlorophyll co- 
incide with the bands of the action spec- 
trum for its own transformation. 

Experiments were performed to obtain 
the absorption spectrum of dark-grown 
barley leaves by use of a Zeiss microspec- 
troscope. Difficulty was encountered, how- 
ever, in seeing the absorption bands ini- 
tially present. As soon as the light for 
observing the bands was turned on, trans- 
formation of the protochlorophyll began. 
Rapid changes in absorption followed 
which were exciting to watch but impossi- 
ble to define. The impression was always 
gained that originally a band existed near 
650 mu which changed rapidly to a band 
near 635 mu and that sometime during the 
few seconds in which these fleeting changes 
were occurring, the chlorophyll band near 
670 mu appeared. This band continued to 
increase in intensity until a sharp, stable 
absorption band existed between 670 and 
690 mu. The weak absorption band near 
635 mu persisted. 

In an attempt to stabilize the original ab- 
sorption bands, etiolated barley leaves were 
killed by immersion in hot water. After 
this treatment there was no transformation 
and a stable band existed in the leaves at 
635 mu. This band was undoubtedly due 



i54 



CARNEGIE INSTITUTION OF WASHINGTON 



to protochlorophyll, but was displaced 
from the action-spectrum maximum at 
650 mp. Because of this and other unac- 
counted-for spectral changes, doubt was 
cast on the heating procedure for maintain- 
ing the spectrum of the living leaf. 

Another tissue than etiolated leaves that 
can be used for determining the absorption 
spectrum of native protochlorophyll is the 
inner coats of squash seeds. In many ways, 
this material is ideally suited to this pur- 
pose: it is translucent; it contains a high 
concentration of protochlorophyll; it does 
not transform protochlorophyll during rel- 
atively long illumination periods; and it 
is readily extracted with organic solvents 
to yield protochlorophyll solutions. 

Examination of inner coats from Hub- 
bard squash seeds by means of a Zeiss 
microspectroscope showed this tissue to 
have absorption bands that agree closely 
with the action spectrum for the transfor- 
mation of protochlorophyll to chlorophyll 
in etiolated corn leaves. The acetone ex- 
tract of this tissue had absorption bands 
which identified the extracted pigment 
with protochlorophyll. The data substan- 
tiating these statements are given in table 1 . 
The similarity between the action spectrum 
for the transformation of protochlorophyll 
to chlorophyll and the absorption spectrum 
of natural protochlorophyll is convincing 
evidence for natural protochlorophyll's be- 
ing the pigment active in the absorption of 
light for the transformation reaction. 

The fluorescence spectra of Hubbard 
squash inner seed coats showed the ex- 
pected protochlorophyll band at 655-660 
mp, but there was from 2 to 10 times as 
intense fluorescence in a band whose posi- 
tion varied from 700 to 710 m|j. Further- 
more, a band at about 638 m|j was also 
present in the fluorescence spectra of ba- 
nana squash inner seed coats and of 
glycerine extracts of the inner seed coats of 



Hubbard squash. Acetone extracts of all 
seed coats, however, showed absorption 
and fluorescence spectra identical with 
those of protochlorophyll. 

This state of affairs, though apparently 
confusing, is probably merely the com- 
bined result of two processes. One of these 
is the change in situ of a part of the normal 

TABLE 1 

Summary of absorption maxima for the 

pigment of the inner seed coats 

of Hubbard squash 

Wave lengths (m/i) 

Action spectrum for the 
transformation of 
protochlorophyll in 
corn leaves 650 593 548 445 

Absorption bands of inner 

seed coats 650 595 550 ... 

Absorption bands of glyc- 
erine suspension of 
ground-up inner seed 
coats (photoelectric) 650 590 

Absorption bands of ace- 
tone extract of inner 
seed coats: 

Visual 625 570 530 ... 

Photoelectric 625 570 530 ... 

Absorption spectrum of 
acetone solution of 
pure protochlorophyll 
(photoelectric) 623 571 535 432 

form of protochlorophyll, which absorbs 
at 650 m\\ and fluoresces at slightly longer 
wave lengths, to the altered form absorbing 
at 635 mp. This efiect is presumed to be 
responsible for the variable amount of 
fluorescence at about 638 m^i. The very 
strong fluorescence found in these deeply 
colored seed coats at 700 to 710 mjj is 
presumably due to a secondary band of 
protochlorophyll. Its great intensity in 
comparison with the "main" peak near 653 
mp is believed to be due to the fact that 
light of these wave lengths is not reab- 



DEPARTMENT OF PLANT BIOLOGY 



155 



sorbed, whereas the "main" peak has been 
nearly obliterated by internal reabsorption 
because it is so close in position to the ab- 
sorption peak of protochlorophyll. This is 
indeed an extreme case of distortion due to 
reabsorption. Perhaps an alternative ex- 
planation based on the existence of an 
unrecognized pigment fluorescing at 700 
to 710 mu may be possible. No such pig- 
ment is, however, extractable by acetone, 
nor does the fluorescence of the acetone- 
extracted residue show any sign of it. 

The Fluorescence Spectra of 
Chloroplast Pigments 

C. S. French 

Measurements of the fluorescence spec- 
tra of red algae were made several years 
ago specifically to study the transfer of 
energy between their various chloroplast 
pigments, as reported in Year Book No. 49 
(1949-1950), page 86, and No. 50 (1950- 
1951), page 122. A new fluorescent pig- 
ment of leaves (Year Book No. 49, p. 99) 
was found to be a porphyrin type of com- 
pound by the characterization of its fluores- 
cence spectrum. These and numerous un- 
published determinations of the curve of 
fluorescence intensity against wave length 
as recorded photoelectrically have been 
made for the purpose of settling specific 
questions in regard to the constitution or 
function of previously recognized pig- 
ments. 

During the course of these investigations 
it has gradually become apparent how re- 
markably little is known about the fluores- 
cence spectroscopy of chloroplast pigments 
in living material. Many of the curves that 
have been measured are not clearly inter- 
pretable without recourse to the entirely 
unproved assumption of the existence of 
previously unsuspected pigments or of un- 
believably great distortion by internal ab- 
sorption of the fluorescence light. Further- 



more, the frequent absence of anticipated 
fluorescence peaks in certain plants, for 
example those of chlorophyll b or chloro- 
phyll c, leads to the question whether this 
absence is due to very efficient transfer of 
energy from these pigments to others, or 
to internal reabsorption of the fluorescence, 
or merely to their low efficiency as fluores- 
cence emitters. 

In brief, it has been our experience that 
the use of fluorescence spectroscopy to 
answer a few questions has raised many 
general problems of basic importance re- 
lating to the interpretation of fluorescence 
spectra. The use of fluorescence emission 
curves in characterizing not only the na- 
ture of the pigment systems in plants, but 
more particularly the functional relations 
between them, is a field that has hardly 
begun to be developed to its potential value 
for investigating photosynthetic pigments 
in their natural state. 

In order to develop the field of fluores- 
cence spectroscopy of photosynthetic pig- 
ments enough to make use of its inherent 
possibilities, several different lines of in- 
vestigation will have to be carried farther 
and correlated with one another. In the 
first place, fluorescence spectra of the com- 
mon chloroplast pigments and of their 
derivatives should be precisely determined 
in the commonly used organic solvents. 
Some of these spectra are available in the 
literature and some have been measured in 
this laboratory, but much routine work re- 
mains to be done in compiling and check- 
ing these reference data for pigment identi- 
fication. In the second place, the fluores- 
cence spectra of the individual pigments in 
living organisms should be obtained. This 
is the more difficult problem. The diffi- 
culties here lie in the fact that except for 
chlorophyll a and protochlorophyll, it is 
hard to find organisms showing only the 
spectrum of a single pigment. Further- 



156 



CARNEGIE INSTITUTION OF WASHINGTON 



more, in order to eliminate errors due to ous substances in plants or in their extracts, 

internal reabsorption, only plant materials does not as far as we know bear directly 

containing low concentrations of the pig- on the nature and function of the pigments 

ments are suitable. Many of these in vivo that are involved in photosynthesis, 
curves for the individual pigments must The apparatus has been improved by the 

be obtained by subtracting curves of installation of the recently available 6217 

known pigments from curves obtained photomultiplier tube and the correspond- 

from organisms containing two or more ing modifications of the correcting mecha- 

fluorescent substances. A third phase of nism, so that the useful range now extends 

the program is the exploration of a wider to 770 m|j rather than to the previous red 

variety of plants that contain both simple limit of 750 mp. The sensitivity is also 

and complex pigment systems. A fourth several times greater than before this 

phase is concerned with establishment of change. The frequency of the tuned ampli- 

suitable conditions and selection of appro- fier has been changed from 150 to 120 

priate plant material for making the meas- cycles per second, and a rotating sector is 

urements, and of suitable means for apply- no longer used for the fluorescence meas- 

ing the necessary corrections. Such factors urements, since the light source itself is 

as the well known change of fluorescence modulated at this frequency. A 120-cycle 

intensity of chlorophyll with time in pho- chopper is, however, used with the stand- 

tosynthesizing cells, and the limiting con- ard lamp for calibration, 
centration of pigments to give curves During the past two years the develop- 

undistorted by absorption, must be con- ments in this program have been of very 

sidered. Furthermore, a single pigment limited scope in comparison with the po- 

may exist in two different forms within tentialities of the subject, although a small 

the cells, as was found to be true of pro- number of new phenomena have been en- 

tochlorophyll. countered. One of the main questions in 

In addition to the biological problems, mind has been to see why the expected 

continual attention must be paid to the fluorescence bands of chlorophylls b and c 

apparatus, to take advantage of recent com- do not appear in the spectra. The fluo- 

mercial developments in optical, electronic, rescence of chlorophyll b has been reported 

and intensity-measuring devices as well as in the older literature in photographic fluo- 

high-intensity light sources. Since the fluo- rescence spectra of several plants. The 

rescence light emitted by living plants is absence of fluorescence of chlorophylls b 

very weak, even small improvements in the and c in our experiments may well be due 

equipment often have a significant effect to the nearly complete transfer of energy 

on the results. to chlorophyll a, which process may per- 

The program is not being followed in haps proceed with an efficiency dependent 

the order here given, but this outline is on the good health of the plant material 

used as a logical framework into which used. We have looked for chlorophyll b 

may be fitted the various pieces of infor- fluorescence in very pale leaves of various 

mation acquired in the course of experi- species, in the hope of avoiding possible 

mentation carried out for many different difficulties due to reabsorption of the fluo- 

shorter-term objectives. We have avoided rescence, which should, owing to the posi- 

the entire field of nonchloroplast pigment tions of the absorption bands, be greater 

fluorescence, which, though it provides re- for chlorophyll b than for chlorophyll a. 

markably sensitive means of detecting vari- These measurements have not led to the 






DEPARTMENT OF PLANT BIOLOGY 



157 



detection of chlorophyll b fluorescence, but 
they have given with greater precision the 
shape of the fluorescence spectrum of chlo- 
rophyll a in its native state. The compila- 
tion of such basic data is essential for 
further progress and has in itself been one 
of our immediate aims. 

Chlorophyll c is found in diatoms and 
certain algae along with chlorophyll a. 
A culture of the diatom Nitzschia Clostrid- 
ium minutissima was kindly given to us 
by Professor C. B. van Niel. Measurement 
of its fluorescence spectrum confirmed the 
earlier finding of other investigators that 
this organism does not show the band of 
chlorophyll c at about 640 mp, where it 
would be expected on the basis of its ab- 
sorption spectrum in organic solvents. In 
addition to the chlorophyll a fluorescence 
spectrum, these diatoms did, however, have 
a peak of 705 mu. At present this is pre- 
sumed to be the long-wave-length second- 
ary band of chlorophyll c fluorescence, 
and the absence of the main band is 
attributed to its reabsorption by chloro- 
phyll a within the cells. Even extremely 
dilute suspensions of the diatoms show 
this behavior, so the reabsorption, if it 
actually is the cause of the band disappear- 
ance, must take place within the individual 
cells. The effectiveness of different wave 
lengths in producing chlorophyll a fluo- 
rescence in Nitzschia showed that fuco- 
xanthin, which has its maximum in vivo 
absorption at about 510 mu, is more effec- 
tive in transferring energy to chlorophyll 
than are the carotenoids, which absorb 
from 400 to 450 mu. 

It should be noted that in the region 
700-710 mu the positions of the fluores- 
cence bands from the diatom N. Clostrid- 
ium minutissima and from inner seed 
coats of squash are very nearly the same. 
These biological materials contain chloro- 
phyll c and protochlorophyll respectively. 
Inasmuch as the absorption spectra of these 



pigments when extracted are similar, as 
well as their in vivo fluorescence spectra, 
an interesting question is raised concern- 
ing the relationship between chlorophyll c 
and protochlorophyll. 

A nearly complete obscuring of the main 
chlorophyll fluorescence peak was found in 
a deep green leaf, Photinia arbutijolia, il- 
luminated with green light (546 mu) 
which penetrates the leaf deeply. With 
blue light, however, 436 mu, absorbed in 
the outer layers of the leaf, the main peak 
and the secondary peak were of equal 
height. These measurements, made in col- 
laboration with Dr. Robert Hill, were later 
confirmed by Dr. Young. This effect is 
an excellent example of the difficulty of 
clearly recognizing the effects of reabsorp- 
tion when using data which taken at their 
face value would appear to indicate that 
all the fluorescence present originated from 
an unknown pigment. 

The fluorescence spectra of a normal red 
alga were compared with those from the 
same alga adapted to red light, in col- 
laboration with Professor Lawrence Blinks 
and Mr. Robert Airth. The red-adapted 
alga gave less fluorescence than the normal 
one in the region around 700 mu, for some 
reason that is not yet clear. 

Dr. Glenn W. Todd measured the fluo- 
rescence spectra of a pigment isolated from 
light-sensitive bluegrass seed, and found 
this pigment to be identical with pheophy- 
tin as to its absorption and fluorescence 
spectra. 

Reversible Changes in the Light Absorp- 
tion of Purple Bacteria Caused 
by Illumination 

L. N. M. Duysens 

Some intermediate products of photo- 
synthesis have a natural lifetime shorter 
than a few seconds. The elucidation of 
the nature and function of these inter- 



!^8 CARNEGIE INSTITUTION OF WASHINGTON 

mediates would probably contribute greatly their growth medium — i per cent peptone, 

to an understanding of the photosynthetic 0.5 per cent sodium chloride — the change 

reactions. It is not feasible to study inter- was zero at low intensities from about 

mediates with such a short life by chemical 10 4 ergs/cm 2 /sec, and increased slowly up 

analysis after extraction. Rather, it is neces- to the highest intensity used, 9 X io 4 ergs/ 

sary to work with living cells, or parts of cm 2 /sec. In this medium, even at the 

cells able to produce intermediates upon highest intensity used, the maximum 

illumination. These intermediates may be change measured was smaller than the 

detected by observing the effects produced greatest change obtained in distilled water, 

by irradiation. Two such effects are fluo- The maximum change in absorption coeffi- 

rescence and luminescence of photosyn- cient at 880 mjj was of the order of 1 per 

thetic pigments. cent. 

A third effect, a change in the absorp- If we assume that the rate of formation 

tion spectrum of a photosynthetic pigment, of the changed state in the light is the 

has been observed. This effect was found same in the presence and in the absence of 

in the Biophysical Research Group at peptone, then the fact that the change ob- 

Utrecht during investigations on the trans- served is smaller in peptone than in dis- 

fer of excitation energy between pigments tilled water shows that the rate of disap- 

in photosynthesizing cells. Such a change pearance of the changed state in dark 

in absorption indicates a change in the pig- reactions must be higher in peptone than 

ment or in adjacent cell constituents. A in water. The high rate of disappearance 

study of this change may throw light on in the presence of peptone may be caused 

the reactions following excitation of chlo- by the reaction of the changed pigment or 

rophyll a in algae or bacteriochlorophyll of a substance causing the changed absorp- 

in bacteria. tion with a product formed from peptone. 

It was found that irradiation of purple This reaction is perhaps a photosynthetic 

bacteria with blue light of high intensity one, since peptone is the substrate used by 

caused a change in their absorption spec- the bacteria for growth in the light. The 

trum. The change was completed within study of the formation and disappearance 

one second. When the cells were darkened, of such an intermediate presumably would 

they reacquired their original absorption provide data important for the elucidation 

spectrum, also within one second. The of the mechanism of photosynthesis. A 

change in absorption in the region 650 to first step in such a study is the measure- 

920 mn indicated that the bacteriochloro- ment of the rate of disappearance of the 

phyll absorption was altered by irradiation, changed state both in the presence and 

The change in the absorption coefficient at in the absence of peptone. For this pur- 

880 mu, the wave length at which the pose the following experiments have been 

effect was maximum, was measured in the carried out at the Department of Plant 

nonsulfur purple bacterium Rhodospiril- Biology. 

lum rubrum strain 4 as a function of the The bacterial suspension was circulated 

intensity of irradiation. If the bacteria in a closed system by means of a centrif- 

were suspended in distilled water, the ugal pump. It was illuminated while be- 

change increased roughly linearly with ing passed through a coil of transparent 

incident intensity until saturation was Tygon tubing, 100 cm long. It then passed 

reached at about 2X10 4 ergs/cm 2 /sec. If, in darkness to an absorption cell where 

however, the bacteria were suspended in the changed absorption caused by illumi- 



DEPARTMENT OF PLANT BIOLOGY 



159 



nation could be observed. The distance Table 2 shows the changes in absorption 
from the end of the coil to the mid-point of for short dark path measured after bub- 
the absorption cell was normally 11 cm. bling the designated gas mixture through 
This distance in darkness could be length- the suspension for about half an hour. The 
ened to 33 cm by covering part of the coil, changes were roughly reversible. 
From comparison of the measurements ob- The table also shows half lives of the 
tained after different durations of dark changed state, calculated on the arbitrary 
period with the measurements obtained assumption that the restoring reaction is 
without illumination of the coil, and from proportional to the number of changed 
the rate of flow of the suspension, 45 cm/ molecules. The fact that the half lives are 
sec, the rate of return of the changed ab- essentially the same suggests that the re- 
sorption to "normal" could be computed, storing reactions occur with the same rates 
This rate was taken as a measure of the for the two oxygen concentrations, al- 
rate of the restoring reactions. 

The light used for the absorption meas- TABLE 2 

urements, wave length 880 mu, was ob- Influence of oxygen on change in absorption 

tained by use of a tungsten lamp and a of purple bacteria when illuminated 

monochromator, and was of such low in- =====^^====^=^== 

tensity as to have no effect on the absorp- Per cent oxygen ^^ ch H a ^ fe st a f te 

tion. The temperature of the reacting sys- in y rogen absorption (sec) 

tern was 30 ° C. ~ 08 ~ 

If the intensity of the light incident on 4 0.32 

the bacteria in the coil was increased, the 14 0.45 1.0 

measured change increased to a limit. In 43 °-? 8 * - 2 

all experiments the intensity of the inci- 
dent light used was great enough to obtain though the changes in absorption are dif- 
this limit. The change in absorption is ferent. 

calculated as the percentage change in ab- To investigate the nature of the action 

sorption coefficient at 880 mu. of oxygen, the change in absorption by a 

The same strain of Rhodospirillum ru- colloidal aqueous suspension of the bac- 
brum that was used in Utrecht, grown in terial material was measured. This ma- 
1 per cent peptone and 0.5 per cent sodium terial was prepared by passing a concen- 
chloride, was used throughout the experi- trated suspension of bacteria at 1400 at- 
ments. It was observed that after centrifu- mospheres pressure through a slightly 
gation and resuspension of the bacteria in opened needle valve (Year Book No. 48, 
0.5 per cent sodium chloride and M/15 1948-1949, p. 88). The larger particles, 
phosphate buffer of pH 6.5, the change in such as cell walls, were removed by cen- 
absorption gradually declined. The original trifugation for 15 minutes at 10 4 times 
change in absorption was restored if the gravity. The clear colloidal suspension 
suspension was removed from the circuit showed an appreciable change in absorp- 
and permitted to stand in contact with air tion, 1.78 per cent, which was reduced 
for some time. This observation suggested only 30 per cent by sweeping with hydro- 
that the effect was caused by oxygen. Vari- gen for 18 minutes. The original change 
ous mixtures of hydrogen and oxygen were in absorption was restored either by vigor- 
bubbled through part of the circuit before ously bubbling oxygen through the sus- 
and during the absorption measurements, pension or by making it 7X10" 3 M with 



i6o 



CARNEGIE INSTITUTION OF WASHINGTON 



potassium ferricyanide as oxidant. The 
phenomena were not influenced by the 
presence of 3X10" 4 M potassium cyanide 
or 0.1 M urethane. 

If one-day-old bacteria are centrifuged 
and resuspended in fresh growth medium, 
in which they may be expected to photo- 
synthesize, their change in absorption is 
negligibly small up to irradiation intensi- 
ties of io 5 ergs/cm 2 /sec. This intensity re- 
fers to the fraction of irradiation of wave 
lengths shorter than 900 mu, where the 
bacteria show strong absorption. On the 
other hand, if bacteria or their extracts are 
in such a condition that they show a meas- 
urable absorption change, this change 
reaches its maximum at intensities between 
5X10 3 and 5X10 4 ergs/cm 2 /sec. Under 
these conditions the half lives of the 
changed states in distilled water with 0.5 
per cent sodium chloride were found to be 
substantially alike in the presence of hydro- 
gen, nitrogen, 2 per cent carbon dioxide, 
and helium. The change in absorption of 
bacterial suspensions was greater at pH 8.0 
than at pH 6.5, and greater without sodium 
chloride than with 0.5 per cent sodium 
chloride. 

The ratio of actinic intensities of blue 
and infrared radiation just sufficient to 
saturate the change in absorption was 
roughly equal to the ratio that was to be ex- 
pected if radiation energy absorbed by or 
transferred to bacteriochlorophyll was re- 
sponsible for the change. 

Our observations can be explained by 
the assumption that a change in absorp- 
tion upon irradiation is observable if a 
certain substance in its oxidized state is 
present in the bacterial system. If this 
substance is reduced, the change in absorp- 
tion becomes too small for measurement 
with our apparatus. It is known that bac- 
teria respire vigorously in a fresh suspen- 
sion supplied with growth medium. They 
may well be able to remove the oxygen and 



bring about the reduction of the oxidized 
substance. This explains why a change in 
absorption is not found under these con- 
ditions. If a change in absorption is not 
observable with our apparatus, the changed 
state may nevertheless be produced but 
with such a short life that the original ab- 
sorption is restored before the suspension 
reaches the absorption cell. 

The Effect of Light on the Consistency 
of Cytoplasm 

Hemming I. Virgin 

Visible light has many different effects 
on normal green plants. Several more or 
less independent light-influenced processes 
are simultaneously going on in the plant 
cell, each having its own characteristic 
action spectrum depending on the pig- 
ment which is active in the process. Some 
of these processes, for example photosyn- 
thesis, require rather high light intensities; 
others, such as phototropism and photo- 
periodism, show great sensitivity to very 
low intensities. The reactions induced by 
low light intensities undoubtedly play a 
role in maintaining the orientation and 
shape of the living plant. 

Some years ago it was found that the 
cytoplasmic viscosity of cells of Elodea 
densa and Spirogyra sp. as determined by 
the centrifuge method fluctuates under 
natural conditions. The fluctuations are 
caused by light and disappear after the 
cells stay 3 days in darkness. The cyto- 
plasm now shows a very high response to 
light, consisting in a rapid decrease of vis- 
cosity when illuminated with strong inten- 
sities, and a slow increase with weak in- 
tensities which can be far below those 
required for photosynthesis. 

The work being carried on at the De- 
partment of Plant Biology has two main 
objectives: first, to determine whether this 
phenomenon is restricted to a few special 



DEPARTMENT OF PLANT BIOLOGY 



161 



plant species or whether it is widespread 
among plants; second, to identify the pig- 
ment responsible for this process by means 
of action-spectrum measurements. 

The cytoplasm of water plants has a 
much lower viscosity than that of land 
plants; consequently a much smaller cen- 
trifugal force is required to displace its 
contents. In order to work with terrestrial 
plants, a centrifuge more powerful than 
the one used previously was constructed. 
With a force of 12,500 times gravity the 
cell contents of most land plants are com- 
pletely displaced within 1 to 4 minutes. 
During the centrifugation, the plant tis- 
sues are placed in small glass tubes meas- 
uring 15X2 mm inside. The centrifuge 
attains maximal speed in 4 seconds and 
can be stopped in an equal time. A short 
braking time is necessary to make observa- 
tion possible before redistribution of the 
cell contents takes place. 

With this centrifuge it has been possible 
to establish the fact that light has a definite 
effect on the cytoplasm of terrestrial plants, 
for example on the leaves of Eschscholtzia 
and on the petioles of Taraxacum. In 
order to have the cytoplasm respond maxi- 
mally, the plants must be kept either in 
very weak light or in darkness for a few 
days. These findings make it likely that 
the effect of light on protoplasmic viscosity 
occurs in many or all plants. Its role, from 
a physiological point of view, has not been 
found. 

The experiments concerning the action 
spectrum for this phenomenon have been 
performed with the Wood grating mono- 
chromator, using a very high-pressure mer- 
cury arc as light source. The results ob- 
tained have confirmed the earlier prelim- 
inary results found with interference filters, 
namely, that the process is activated mainly 
by blue light. The effect is restricted to 
wave lengths from about 400 to 500 mu, 
with peaks of activity at 450 and 480 mu. 



Exploratory experiments have failed to 
show any response to infrared radiation. 
The spectral region of greatest activity 
corresponds to that absorbed most strongly 
by the carotenoids and by riboflavin-like 
pigments. It is possible, therefore, that the 
pigment active in changing the viscosity of 
protoplasm belongs to one of these classes, 
which have been postulated to play a role 
in the better-known phototropic response, 
to which this phenomenon may be related. 

Up to the present time, the displacement 
of the cell contents has been determined by 
visual microscopic examination of the plant 
tissue. In the hope that a more objective 
method of measurement might be devised, 
the light transmission of illuminated and 
centrifuged Elodea leaves was measured 
and compared with that of unilluminated 
leaves. The transmission was changed 
only a few per cent by the treatment of 
the leaves. Consequently, this method of 
measurement did not seem promising for 
practical use. 

The possibility exists that the light-in- 
duced changes in the viscosity of the cyto- 
plasm may affect the rigidity of the irra- 
diated tissue. To test this possibility, a 
method of measurement was suggested by 
Dr. Bush which is based on the principle 
that the oscillation frequency of a vibrat- 
ing rod depends on its rigidity. In the ex- 
perimental set-up a small piece of plant 
tissue was fastened at one end between two 
glass plates. To the other end was attached 
a very small steel plate. The tissue was 
placed in front of an electromagnet fed 
with alternating current at various fre- 
quencies from an oscillator. If the turgor 
of the tissue was altered by dipping it in 
sucrose or salt solutions of various concen- 
trations, significant changes occurred in 
the frequency which gave the maximum 
vibration. But when the rigidities of il- 
luminated and unilluminated tissues were 
measured, no difference was found be- 



1 62 



CARNEGIE INSTITUTION OF WASHINGTON 



tween the two. The light-induced altera- 
tion in consistency of the cytoplasm is 
therefore probably very small in compari- 
son with the rigidity of the leaf, which is 
determined mainly by the turgor pressure 
of the cytoplasm on the cell walls. This 
experimental procedure may perhaps be of 
use in the investigation of osmotic effects 
in living material. 

The Curve Analyzer 

C. S. French, W. R. Fair, R. M. Cook, 
W. W. Holt, and Elwin W. Seeley 

The machine for converting curves and 
plotting equations (Year Book No. 49, 
1949-1950, p. 100; No. 50, 1950-1951, p. 133; 
No. 51, 1951-1952, p. 154) that has been 
under construction since January 1950 has 
been developed to the point of reasonably 
reliable operation, and no further extensive 
expansion or alterations are contemplated 
at present. Its functional units now consist 
of a voltage source increasing linearly with 
time, which is used as the independent 
variable, and of five curve followers, nine 
adding amplifiers, three amplifiers used 
for curve multiplication, two integrators, 
and a recorder. There are also power sup- 
plies and amplifiers necessary for the oper- 
ation of the fourteen servo systems driving 
the tables, followers, integrators, and re- 
corder. Since one integrator shares the 
servo amplifiers of one follower, only four 
followers can be used if both integrators 
are required. The operational units may be 
connected in any desired way for the trans- 
formation or analysis of curves or as an 
analogue computer for plotting the solu- 
tion of equations. 

A general view is shown in plate 1. In 
this picture the rack at the left contains the 
power supplies, the next one is a curve-fol- 
lower unit with its table at the bottom 
position, and the second follower unit, 
bearing the curve y — e~ x , has the table at 



the top of its range. The next rack, with 
the white base, is the recorder, which is 
similar in construction to the curve fol- 
lowers. On its right is the main control 
rack, carrying the independent variable 
voltage supply, the adding amplifiers, and 
one integrator with its driving amplifiers. 
It also has a small patching panel on the 
side, so that certain analogue voltages may 
be measured or their interconnections 
changed from the operator's position, al- 
though most of the connections are made 
on the rear of the control rack. The three 
curve followers to the right of the control 
rack are shown with normal probability 
curves on their tables in the way in which 
they are used to synthesize a complex 
curve of adjustable shape. Follower num- 
ber three, to the right of the control rack, 
also carries the second integrator just be- 
low the bottom of the table travel. Both 
integrator assemblies can be pulled out on 
roller slides to make them accessible when 



in use. 



During the past year the last two fol- 
lowers were completed, the second integra- 
tor was installed, and most of the ampli- 
fiers were modified. The major change, 
which has greatly improved the perform- 
ance with problems involving cascaded am- 
plifiers, has been the incorporation of 
trimming condensers to correct for slight 
phase shift of the analogue voltage at each 
amplifier input. The addition of means for 
adjustable damping of the follower car- 
riage servo systems and an improved set- 
ting procedure has removed the need for 
frequent readjustment. New paraphase 
amplifiers were built for use in curve mul- 
tiplication and are entirely satisfactory. 

The device has been tested with a 
variety of problems, mainly those that oc- 
cur in connection with other work of the 
laboratory, and has been used extensively 
for the recalculation of recorded curves of 



Department of Plant Biology 



Plate t 




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DEPARTMENT OF PLANT BIOLOGY 



l6 3 



fluorescence spectra. A description of the 
machine, including records of sample prob- 
lems, is being prepared for publication. 

The following persons rendered valuable 
services in connection with the construc- 
tion of the curve analyzer during the year: 
Messrs. Arthur B. Dennis, Alfred M. 
Faries, Euyen Gott, Louis H. Rorden, and 
particularly Louis R. Kruger. 

Growth of Chlorella in Intermittent 
Light 1 

J. Neal Phillips, Jr., and Jack Myers 

Last year's report included several studies 
concerned with turbulence and the inter- 
mittent-light effect on growth of Chlorella 
(Year Book No. 51, 1951-1952, pp. 137- 
140). One of these studies has been ex- 
tended and the practical and theoretical as- 
pects of the data have been examined. 

Attempts at mass culture of algae have 
posed the problem of increasing the effi- 
ciency of utilization of the high intensity 
of sunlight for photosynthesis and growth. 
Efficiency of utilization of high light in- 
tensity by the photosynthetic process is 
known to be increased when the light is 
presented in very short flashes separated 
by long dark periods. In a dense culture 
under sunlight illumination, individual 
cells are subjected to a regime of intermit- 
tent illumination which depends on the 
thickness and density of the suspension and 
the degree of turbulence. The question 
therefore arises as to the proper regime 
of intermittence to be provided by turbu- 
lence in order to take advantage of the 
flashing-light effect. 

A constant-density, constant-volume 
method was devised for measurement of 
the specific growth rate in a very dilute 
algal suspension illuminated with light 
from a tungsten lamp at a color tempera- 

1 This work is being done at the University 
of Texas. 



ture of 2900 ° K and at a maximum inten- 
sity of 25 X io 4 ergs/cm 2 /sec in a focused 
optical system. The maximum intensity, 
which was nearly twice that required for 
saturation, could be decreased by use of 
neutral niters to provide various intensities 
of continuous illumination, or the light 
beam could be chopped by a set of rotating 
sectors to give light flashes of 1, 4, 16, or 
67 milliseconds combined with various 
dark periods. 

For practical purposes the data may be 
treated by comparing the growth rate pro- 
duced by short flashes of high intensity 
with the growth rate under an equivalent 
amount of energy supplied continuously at 
a lower intensity. The comparison pro- 
vides a measure of the degree to which 
Chlorella pyrenoidosa can integrate inten- 
sity X time for any intermittent-light regi- 
men. With 1 -millisecond light flashes the 
integration is essentially complete, since for 
any value of integrated intensity the 
growth rates are the same in intermittent 
as in continuous light. As the flash time is 
increased from 1 to 4 to 16 to 67 milli- 
seconds, the degree of integration becomes 
progressively lower. It is significant, how- 
ever, that even with a 67-millisecond flash 
there is some integration and therefore 
some gain in efficiency of utilization of 
high light intensity. The data predict that 
a dense algal culture growing under sun- 
light illumination will experience a signifi- 
cant increase in growth if the turbulence 
is sufficient to move cells in and out of the 
front surface at such a rate as to give flash 
times between 0.001 and 0.1 sec. 

For theoretical treatment, the specific 
growth rate, \, may be converted to 
^/flash, or to the equivalent unit of 
mm 3 2 /mm 3 cells/flash used in manomet- 
ric experiments of photosynthesis studies. 
Yield per flash for any flash time may then 
be plotted against length of the intervening 



164 



CARNEGIE INSTITUTION OF WASHINGTON 



dark period. Classic flashing-light theory, 
developed from the well known experi- 
ments of Emerson and Arnold, predicts 
that for flashes of saturating intensity the 
yield per flash will increase with increasing 
dark times and will approach a maximum 
yield which is independent of any charac- 
teristic of the flash itself. The present data 
show that as the light flash is lengthened 
from 1 to 67 milliseconds, the maximum 
yield per flash and the dark period neces- 
sary to attain maximum yield are continu- 
ously increased. Furthermore, the maxi- 
mum yields per flash and the necessary 
dark periods are much greater than those 
observed by Emerson and Arnold with 
their 0.01 -millisecond flashes. The present 
data are compatible with those of Tamiya, 
obtained from studies on photosynthesis 
with 1- to 8-millisecond flashes; they are 
not compatible with classic flashing-light 
theory even when corrections are made for 
the amount of photosynthesis and growth 
occurring during the appreciable length of 
the light flashes. It is concluded that there 
is some unrecognized limitation in the 
classic flashing-light theory or that some 
new phenomenon is introduced by the use 
of longer light flashes. 

Selection of Algae Adapted to Large- 
Scale Algal Culture 2 

Jack Myers 

The problem of commercial large-scale 
culture of algae has been approached as a 
problem of applied photosynthesis, that is, 
the utilization of sunlight in the produc- 
tion of organic matter. Both laboratory 
and pilot-plant experimentation have used 
well known species of Chlorella or Scene- 
desmus as the algal material. The problem 
may be approached also as one of applied 
microbiology. Attention then is focused on 
the importance of obtaining different spe- 

2 This work is being done at the University of 
Texas. 



cies or strains of algae that are advanta- 
geous in their particular responses to en- 
vironmental conditions or in their capac- 
ities for production of special materials. 
The possibilities, limitations, and accom- 
plishments of the second line of approach 
are the subject of this report. 

Selection of algal strains for special re- 
sponse to environmental conditions. For 
mass-culture applications, the most impor- 
tant environmental conditions are tem- 
perature, light intensity, and composition 
of culture medium. 

An encouraging beginning in the selec- 
tion of special algal strains was made by 
Sorokin's isolation of a number of strains 
of Chlorella with higher temperature op- 
tima than those of the strains generally 
used (Year Book No. 51, 1951-1952, p. 
141). The question of the basic reasons for 
the marked difference in temperature op- 
tima, 25-26° C for the standard Chlorella 
pyrenoidosa and 38-39° C for one of the 
new strains labeled Tx 71 105, is now under 
study. At 30° C the standard Chlorella 
pyrenoidosa will not grow indefinitely, but 
will show high and only slowly decreasing 
rates of respiration and photosynthesis for 
many hours. It is inferred that temperature 
optima for growth are governed, not by 
photosynthetic or respiratory processes per 
se, but by some more sluggish mechanism 
such as the balance between rate of forma- 
tion and denaturation of enzyme systems. 
The time characteristics of response of 
metabolic processes to different tempera- 
tures are being studied in comparing the 
two strains. 

The ease and success of Sorokin's iso- 
lation of strains of Chlorella with high 
temperature tolerance has led to similar at- 
tempts with the blue-green algae. The 
combined efforts of Mr. William A. Kratz, 
of our laboratory in Texas, and Dr. Mary 
Belle Allen, of the Hopkins Marine Sta- 
tion, have led to isolation of a blue-green 



DEPARTMENT OF PLANT BIOLOGY 



I6 5 



alga tentatively identified as Anacystis rates or physical characteristics which make 
nidulans. At the optimum temperature, them useful for mass-culture applications, 
tentatively established as somewhere be- A search for desirable nitrogen fixers is 
tween 40° and 44° C, it has a growth rate now being made by setting up accumula- 
comparable with that of Sorokin's high- tion cultures in nitrogen-free media from 
temperature strain of Chlorella. Kratz is rice-field inoculations. Chlorella is unusu- 
now engaged in a study of Anabaena, Ana- ally versatile in its tolerance of variation of 
cystis, and other blue-green algae under a pH and salt concentration; other algae are 
grant from the National Science Founda- known to have restricted tolerance limits, 
tion. The information should prove useful It may be expected that many of the fresh- 
in affording a background for the possible water planktonic forms will be restricted 
mass culture of blue-green algae. to rather low salt concentrations. Little 

The need for selection of algae particu- attention has been paid to the marine algae, 

larly adapted to high light intensity is illus- although these would have obvious ad- 

trated by a limitation experienced with the vantages for mass-culture applications, 

standard Chlorella. In a dense culture the Selection of algal strains for the produc- 

average light intensity per cell is low, even tion of special materials. The search for 

under sunlight illumination. At this low algae having a particular response to an 

average light intensity each cell produces environmental condition may be carried 

so much chlorophyll that it absorbs some- out generally by conventional accumula- 

where between 10 and 20 times more light tion-culture methods so designed as to give 

than it can use efficiently when it is ex- a selective advantage to those algae having 

posed momentarily to full sunlight. The the desired characteristic. In the search for 

property of producing an abundance of algae producing special materials, however, 

chlorophyll is a distinct disadvantage for there is seldom any selecting principle 

purposes of mass culture. The most desir- which may be imposed. The procedure 

able organism would be one which has the must be the laborious one of screening 

same quantum efficiency as Chlorella at many algae, already isolated, for some 

low light intensities, but so little pigment desirable feature of their composition, 

that it would require full sunlight intensity Models for necessary procedures are pro- 

to attain light saturation. There is, of vided on the one hand by the study of 

course, no certainty that such an organism sterol content of various algae by Krauss 

exists, but it might be sought among plank- (Year Book No. 51, 1951-1952, pp. 142- 

tonic algae which in nature grow under *45)> and on tn e other hand by the inten- 

full sunlight intensities. sive search for antibiotic-producing micro- 

In selection of algae adapted to particu- or g ani sms now being carried on by the 

lar nutritional requirements, the important fermentation industries, 
considerations are the nitrogen source, pH, 

and total salt concentration. Chlorella will SpECIES OF Algae Adaptable to Mass 

I TTT TTTTJTT 

utilize ammonia, nitrate, and urea as nitro- 
gen sources, but not all algae are equally Robert W. Krauss and Donald H. Boughton 
versatile. The most desirable organism Studies in various laboratories concern- 
would be one capable of nitrogen fixation ing the growth of green algae in large- 
as observed in certain blue-green algae; scale cultures have involved species of 

unfortunately, the nitrogen fixers now * TMs work is being done at the University of 

available in culture do not have growth Maryland. 



i66 



CARNEGIE INSTITUTION OF WASHINGTON 



Chlorella as the principal test organisms. 
The choice of Chlorella has been logical in 
view of its well known high growth rate 
and its capacity for altering its chemical 
composition under different environmental 
conditions. Other unicellular or colonial 
species of algae may, however, prove equiv- 
alent or superior to Chlorella for mass cul- 
ture. In order to determine how widely 
applicable mass-culture techniques may be, 



solution plus micronutrients. A mixture 
of 5 per cent C0 2 in air was supplied, with 
tap water flowing through stainless steel 
tubing to hold the temperature at satisfac- 
tory levels. The algae were harvested by 
centrifugation and stored in a deep freeze. 
Table 3 gives the average daily fresh- 
weight yield per liter of ten species of algae 
cultured during the fall and early winter 
of 1952. With the exception of Scenedes- 



TABLE 3 
Total harvest weight and yield of algae grown in mass culture 



Total fresh wt. 
(g) 



Species and source 



Yield, fresh wt. 
(g/l/day) 



Carboys 



Vats 



Carboys Vats 



1,100 


0.076 


0.036 


1,232 


0.071 


0.038 


1,075 


0.157 


0.087 


739 


0.200 


0.115 


872 


0.093 


0.046 


1,761 


0.117 


0.092 


1,309 


0.084 


0.044 


1,625 


0.233 


0.123 


360 


0.227 
0.076 


0.064 



10,073 



Ankistrodesmus Braunii (Pringsheim 202/7b) 715 

Ankistrodesmus falcatus (Pringsheim 202/3) 720 

Asterococcus superbus (Pringsheim 3 /3a) 906 

Chlamydomonas applanata (Pringsheim 11/2) 1,010 

Coccomyxa simplex (Pringsheim 216/9a) 637 

Coelastrum proboscidium (Van Niel Z.4.1.1) 800 

Palmellococcus miniatus (Van Niel Z.l 1.1.1) 631 

Scenedesmus sp.* (Van Niel Z. 14.4.1) 1,285 

Selenastrum minutum (Pringsheim 278/3) 1,719 

Stichococcus bacillaris (Van Niel Z. 15. 1.1) 509 

Totals 8,932 

* Not identified. 



and to produce significant quantities of mus sp. (Van Niel Z.14.4.1), cultured dur- 

other species of algae for analytical pur- ing both periods, these data do not include 

poses, a screening program for species yields for the species of algae reported 

other than Chlorella has been conducted, earlier (Year Book No. 51). 

The culture method and apparatus have Rigorous comparisons of growth in cul- 

been described previously (Year Book No. tures subjected to daily and seasonal vari- 

51, 1951-1952, pp. 142-145). The culture ations in light are not justified. In general, 

vessels, consisting of three 400-liter vats however, the culture conditions were simi- 

and thirty 18-liter carboys, were installed in lar and the yields are a valid comparative 

a greenhouse and received only natural measure of performance. Ten dry-weight 

illumination. Inocula were obtained from determinations indicated an average water 



pure cultures maintained on agar slants. 
Concentrated cultures were grown in Er- 
lenmeyer flasks in the laboratory prior to 
inoculation of the vats and carboys. All 



content of 70 ±7 per cent for the frozen 
samples of algae. This did not apply to 
Selenastrum minutum, which came from 
the centrifuge as a viscous liquid with a 



cultures were grown in a modified Knop's high water content. The mucilaginous cell 



DEPARTMENT OF PLANT BIOLOGY 



167 



wall appears responsible for the poor sep- we have clear-cut evidence of essentiality 
aration from the medium. Attempts to for algal growth are iron, manganese, zinc, 
obtain heavy inocula in flask culture copper, and calcium. Cobalt may be in- 
proved unsuccessful for the following spe- eluded in the list by virtue of its incorpora- 
cies: Dunaliella salina, Euglena gracilis tion in vitamin B12. Molybdenum also has 
var. bacillaris, Haematococcus pluvialis, been proposed for certain algae, but 
Navicula sp., Nitzschia jrustulum, Oocystis whether this requirement holds for all 
Naeglii, Selenastrum bibraianum, and Tri- classes remains uncertain. Failure to sup- 
bonema aequale. It is possible that media ply any one of the essential elements in 
containing other than the strictly inorganic sufficient quantity either reduces growth 
nutrients employed in these experiments or halts it. The problem of supplying the 
would sustain the more rapid growth re- organism with a sufficiency of the metals 
quired for mass culture. Modification of cannot, however, be solved simply by add- 
the inorganic medium, however, by ad- ing them to the medium. Evidence has 
justing concentration and pH and adding been obtained by several investigators that 
silicon in the case of the diatoms, was not certain micronutrients become biologically 
sufficient. unavailable shortly after their incorpora- 

The yield data indicate that although tion into the nutrient solution. This phe- 
numerous species may be grown readily in nomenon may explain the progressive re- 
large-scale culture under natural illumina- duction in yield from continuous mass cul- 
tion, their productivities will differ. More tures of algae which demonstrate a high 
rapid growth from any one species could yield only during the early period of 
be expected only after intensive investiga- growth. 

tion of nutrient requirements. Genetic bar- Numerous techniques have been devised 
riers to rapid cell division undoubtedly in an effort to prevent the displacement of 
exist in many species, making their ex- the trace metals, especially iron, from solu- 
ploitation even in ideal media technically tions by co-precipitation. Among these the 
difficult. Analyses of the samples now un- nonmetabolizable chelating agent ethylene- 
der way, however, may indicate organic diamine tetraacetic acid (EDTA) is the 
constituents of sufficient value to warrant most promising. Its chelating or complex- 
further study of certain species. ing property prevents precipitation, but 

permits sufficient release of minute amounts 

Chelated Micronutrient Levels for of the micronutrients for plant metab- 

SCENEDESMUS 4 olism. 

Robert W Krauss ^he use °^ EDTA is attended with some 

A , , , -it difficulties. Potassium does not form a 

A problem commonly met in the culture , , . , -^t^^ A 1 1 

f 1 1 r 1 • 1 1 11 • chelate with EDI A, and the magnesium 

or algae and or higher plants as well is 1 1 • 11 1 1 • 1 i- 

, ,? . 1 1 • c ano - calcium chelates have high dissocia- 

the limitation on growth resulting from . ~, . , 

, r . t, , .,. , . , . tion constants. I his means that macronu- 

dehciency or unavailability or essential in- . .„ , , , • 1 1 

'. , , trients will probably not compete with the 
organic micronutrients. With the excep- . . £ , ., , , t-t^t- a 

. 1-11 if micronutrients tor the available ED 1 A. 

tion or boron, which has not been clearlv n-u j- r l • 

, . ; lhe dissociation constants tor the micro- 

shown to be essential for algae, these micro- . • . 1 .1 1 1 1 

. . r . nutrients, however, though much lower, 



nutrients are all metals. Those for which 

4 This work is being done at the University of 
Maryland. by the cells, and in turn released by mass 



are not identical, so that as they are ab- 
4 This work is being done at the University of sorbed at different rates from the medium 



i68 



CARNEGIE INSTITUTION OF WASHINGTON 



action from the complexes, competition of 
residual EDTA for the remaining metals 
will occur. The dissociation constants, 
listed in the order of increasing degree of 
stability, for the complexes at 20 ° C in 
0.1 N KC1 are as follows: magnesium, 
2.04 Xio -9 ; calcium, 2.56 Xio -11 ; manga- 
nese, 3.40 Xio~ 15 ; iron (ferrous), 6.02 X 
io~ 15 ; cobalt, 7.95x1c -17 ; zinc, 2.63 Xio -17 ; 
copper, 4.17 Xio -19 ; and iron (ferric), iX 
io~ 25 . A greater quantitative requirement 
for one element, such as iron, will release a 
progressively larger amount of EDTA, 
which must of necessity reduce the avail- 
ability of the remaining metals. This con- 
sideration is further complicated by lack of 
information concerning the equilibria at- 
tained when a number of different ions 
are in competition for EDTA at various 
pH values or in the presence of different 
buffers. Ideally, if the known dissociation 
constants did hold for multimetallic solu- 
tions, the most desirable chelating agent 
would be one in which the order of dis- 
sociation paralleled the order of quantita- 
tive ion absorption. Sufficient information 
concerning quantitative absorption and 
multi-ionic equilibria does not yet exist, 
however, to permit calculation of a precise 
formula for supplying micronutrients as 
chelates to algae. Until this can be done it 
appears advisable to determine experimen- 
tally the levels of chelated micronutrients 
which give maximal growth. 

The multiple culture apparatus previ- 
ously described (Year Book No. 51, 1951- 
1952), modified to provide a maximal ir- 
radiance of 400 foot-candles, from 4500° 
white fluorescent tubes, has been employed 
in this study. The culture vessels have 
been redesigned and are now equipped 
with ground-glass joints, allowing for 
greater protection against contamination. 
Macronutrients were supplied as potas- 
sium nitrate, magnesium sulfate, and 



potassium-dihydrogen phosphate. Before 
autoclaving, the micronutrients were in- 
troduced individually from stock solutions 
of reagent-grade inner-complex salts of 
EDTA. An inoculum of Scenedesmus ob- 
liquus, washed three times in double-dis- 
tilled water, gave an initial packed cell 
volume of 5 X io~ 5 ml/100 ml to each cul- 
ture. The temperature was maintained at 
25° C. The cultures were supplied with 
5 per cent C0 2 in air at the rate of 0.5 
liter per hour per culture of 200 ml. 

TABLE 4 

Effect of various concentrations of the 
inner-complex salts of calcium, manga- 
nese, cobalt, zinc, copper, and iron with 
ethylenediamine tetraacetic acid on the 
growth of Scenedesmus obliquus in the 
presence of a complete macronutrient 
solution 



Concentration 


Concentration 


Packed cell 


of total metals 


of each metal 


volume per 100 ml 


(ppm) 


(ppm) 


after 10 days 








0.065 


6 


1 


1.275 


18 


3 


1.225 


54 


9 


0.975 


162 


27 


trace 


486 


81 


0.000 



With EDTA, a maximum increase in 
total growth of 25 per cent was measured 
as compared with cultures which were 
supplied micronutrients in the form of 
chlorides, nitrates, and sulfates. This in- 
crease was observed both in the multiple 
culture apparatus and in mass cultures. 
Levels up to 500 ppm of each metal were 
tested. Growth ceased at and above 100 
ppm. The results of experiments, with 
concentrations under 100 ppm, are given 
in table 4. 

The optimal range for growth was be- 
tween 1 and 9 ppm for each micronutrient 
or between 6 and 54 ppm of all the micro- 
nutrients. It is likely that the inhibition of 



DEPARTMENT OF PLANT BIOLOGY 



169 



growth observed at the higher concentra- 
tions is due to a toxic effect of the metal 
complement and not to the effect of one, 
such as copper, which might be toxic per 
se. This hypothesis has been tested by 
experiments in which the concentration of 
the copper chelate was varied, with each of 
the other chelates held at 1 ppm. The re- 
sults indicate that the optimum level for 
copper is 3 ppm but that growth at higher 
concentrations is impaired very little, be- 
ing reduced by only 31 per cent at a copper 



concentration of 81 ppm. Experiments to 
determine the optimal and inhibitory levels 
of each of the other micronutrients are 
under way. These data should make pos- 
sible a micronutrient formula of wide ap- 
plicability in the culture of algae. In con- 
junction with the production of large 
quantities of algae in mass culture, it is 
hoped that this technique may provide 
quantitative data on micronutrient require- 
ments and absorption under conditions of 
maximal growth. 



EXPERIMENTAL TAXONOMY 

During the current year efforts have in new plantings at Stanford and at the 
been directed toward the completion of the mountain transplant stations of the Insti- 
Poa program and the development of new tution. Several new hybrid strains of 
programs. Numerous conferences were promise were discovered, adding to the 
held between members of the staff and number previously obtained. For sources 
governmental and private agencies con- of seed of the many new Poa strains we are 
cerning the most effective means of de- almost completely dependent on the Nurs- 
veloping the new hybrid Poa lines al- ery Division of the Soil Conservation Serv- 
ready produced and of familiarizing plant ice, which, during the past year, has 
breeders with techniques of producing new carried on an active program of new plant- 
lines of their own. From these discussions ings for seed increase of the hybrid Poas. 



a co-operative research program has been 
developed with the Department of Agron- 
omy of Purdue University, Lafayette, Indi- 
ana, and furthermore, a ten-state testing 
program of the new Poa lines will be un- 
dertaken by the Division of Forage Crops 
and Diseases of the U. S. Bureau of Plant 



Hybrids produced during a second pe- 
riod of crossing in 1951 became mature in 
the Stanford garden this year, and many 
were cloned for testing at the altitudinal 
transplant stations of the Institution. The 
data from these hybrids are needed for 
completing the basic biological studies on 



Industry. Other developments include the Poa, and it is anticipated that other agen- 

initiation of screening tests of new Poa cies may undertake further development of 

hybrids by the Department of Agronomy any new strains that may have agronomic 

of the University of California at Davis, interest. 

California, and of some strains for turf and A detailed analysis of the complex ge- 
range uses by the Ferry-Morse Seed Com- netic systems controlling the morphological 
pany at Mountain View, California. expression of characters in contrasting 
Hybrid lines developed from the first climatic races of the diploid species Poten- 
series of crossings, performed during the tilla gland ulosa in three environments was 
period between 1943 and 1945, were further concluded, and the results have been as- 
studied in the extensive plantings at the sembled in manuscript form. It was found 
Nursery Division of the Pacific Region of that the genetic systems of ecologic races 
the U. S. Soil Conservation Service, and are even more complex than preliminary 



170 



CARNEGIE INSTITUTION OF WASHINGTON 



analysis had indicated. The characters of 
these climatic races are regulated by series 
of multiple genes of different strength and 
of opposing action, and of complementary 
and activating genes, and of genes that ex- 
press themselves only in certain environ- 
ments. Only by a study of cloned indi- 
viduals of the F 2 hybrid generation in 
three contrasting environments over a pe- 
riod of years combined with an analysis of 
segregation in F3 populations was it pos- 
sible to interpret the apparently conflicting 
lines of evidence. This is the first time 
that a genetic analysis has been carried out 
on such a scale in more than one environ- 
ment, and the results emphasize gaps in 
our knowledge concerning the expression 
of gene influences in different environ- 
ments. 

Another approach to the study of the 
genetic structure of ecologic races is being 
developed in Mimulus. Two diploid spe- 
cies, M. car din alts from low altitudes and 
M. Lewisii from alpine environments, were 
intercrossed, and many Fi hybrids have 
been obtained. These will be used as a 
starting point for genetic analyses of these 
morphologically and ecologically contrast- 
ing racial complexes, utilizing the trans- 
plant stations. It is also planned to use 
these plants in connection with a compara- 
tive physiological study of these contrast- 
ing altitudinal races and their segregating 
progeny. 

Similar studies are being made on hy- 
brids between contrasting climatic races of 
Achillea lanulosa which are tetraploid 
and which therefore probably have more 
complex genetic systems. During the year 
a series of Fi hybrids between lowland and 
subalpine or alpine races of A. lanulosa 
has been produced for this purpose. 

Substantial progress in the construction 
of an apparatus for comparative studies of 
individual physiological processes in plants 



over a range of controlled environmental 
conditions has been made this year. It is 
hoped that this equipment will lend itself 
to comparative studies on contrasting eco- 
logical races and on hybrid progenies as a 
step in the analysis of the relation between 
physiological differences and gene differ- 
ences, especially as regards characters of 
significance in natural selection. 

Starting in September 1952, Grun began 
a year's study at the laboratory of Professor 
T. O. Caspersson at the Karolinska Insti- 
tute in Stockholm, Sweden, in order to 
study the chemical composition of cell con- 
tents by the methods developed by Dr. 
Caspersson. Ultraviolet microspectropho- 
tometric techniques are used to determine 
the nucleic acid and protein contents of 
cells in both a dividing and a nondividing 
state. The purpose is to gain a better un- 
derstanding of the biochemical and phys- 
ical changes taking place during cell di- 
vision. 

The Sixth International Grasslands Con- 
gress, held at Pennsylvania State College 
August 17 to 23, 1952, was attended by 
Clausen and Grun, at which time Clausen 
presented a paper on "New bluegrasses by 
combining and rearranging genomes of 
contrasting Poa species." Clausen and 
Hiesey also attended the Western Grass 
Breeders' Conference at Mandan, North 
Dakota, June 22 to 24, 1953, where Clausen 
presented a paper describing the Poa pro- 
gram of the Institution. These conferences 
offered opportunities to discuss the grass- 
breeding investigations with agronomists 
from different regions within the United 
States and also from other countries. 

The Poa Program 

Jens Clausen, William M. Hiesey, and 
Malcolm A. Nobs 

A review of the progress of the range- 
grass breeding program begun in 1943 was 



DEPARTMENT OF PLANT BIOLOGY 



171 



included in the annual report of last year, and the Carnegie Institution, and have em- 

During the current year, thought and phasized the interdependence involved in 

effort have been directed toward conclud- this co-operation. The present stage of 

ing this program, with the objective of development seems to warrant an exten- 

making available to the public the gains sion of co-operation also to other agencies, 

made both in basic research and in poten- especially state experiment stations and the 

tially valuable new hybrid strains of blue- U. S. Bureau of Plant Industry, whose 

grasses, and at the same time of conserv- scope of activity includes the breeding and 

ing the efforts of the staff so that their time selection of forage plants, 
may be devoted more completely to funda- Such extended collaboration is aimed at 

mental biological investigations. The con- stimulating interest in the practical po- 

traction of this program can most eflfec- tentialities of breeding new apomictic blue- 

tively be accomplished through gradual grasses through wide interspecific crossing, 

steps whereby other agencies well qualified and also at making possible widespread re- 

to deal with practical agronomic prob- gional tests under current agronomic prac- 

lems may take over aspects of the work tices. It was natural to start in California, 

carried by the Institution that fall natu- where many of the strains have been 

rally within the scope of their activities. developed. Accordingly, through Dr. R. 

The contributions of the Carnegie Insti- Merton Love, the Department of Agron- 
tution in its grass-breeding program fall omy of the University of California has 
into two classes: first are the discoveries established small plot tests at the Univer- 
of basic biological importance that clarify sity Farm at Davis, California, using 30 
our understanding of the evolutionary pat- new hybrid lines and parent strains of Poa 
terns and forces operating in apomictic developed by the Institution in co-opera- 
genera, and also furnish essential informa- tion with the Soil Conservation Service, 
tion to the plant breeder; second are the Another co-operative program has been 
new hybrid strains of Poa that have been established with members of the Depart- 
stabilized through apomixis and that may ment of Agronomy at Purdue University, 
have economic value either in their present Dr. A. L. Peterson, head of the Depart- 
state of development or when combined ment of Agronomy at Purdue, and Dr. 
in still untried new crossing combinations. H. H. Kramer, cytogeneticist in the same 

The large backlog of information which Department, visited the Poa plantings at 

has been accumulated and is still growing the Stanford and Mather stations as well 

must be analyzed and published in sum- as the Soil Conservation Service nursery 

marized form in order that the basic at Pleasanton, California, during May of 

knowledge that has been gained may be the current year. They plan a sustained 

available both to scientists and to practical research program to explore the possibili- 

plant breeders. This obligation in itself ties of developing new strains particularly 

will require considerable time and effort, suited to meet their requirements in Indi- 

The problem of making the best possible ana and adjacent regions. Steps have been 

use of the strains and new hybrids of Poa taken to establish a fellowship supported 

already developed has been given detailed jointly by the Carnegie Institution of 

consideration, and steps have been taken in Washington and the Purdue Research 

this direction. Previous Year Book reports Foundation for the special training of 

have described the close co-operation be- qualified young agronomists in the tech- 

tween the U. S. Soil Conservation Service niques of developing new strains through 



172 



CARNEGIE INSTITUTION OF WASHINGTON 



wide interspecific crossing of apomictic Poa scabrella X P. pratensis originating 

lines. This program is being started with from a segregating, sexual F 2 progeny, 

a detailed screening test of the available These scabrella-pratensis F 2 derivatives 

apomictic lines of Poa for possible direct were among the few scabrella-pratensis 

use in Indiana or for further crossing. survivors at Pullman after a mild January 

A comprehensive regional screening of followed by a cold February without snow 
the more promising Poa strains that have that eliminated whole blocks of strains 
been stabilized through apomixis is being previously thought to be winter-hardy, 
developed by Dr. A. A. Hanson, of the The new lines are much more winter- 
Office of Forage Crops and Diseases of the hardy and vigorous than are derivatives of 
U. S. Bureau of Plant Industry. In this scabrella-pratensis of this same combina- 
test some 30 of the more promising Poa tion previously grown at Pullman, and 
lines will be planted in replicated test their morphological characters suggest that 
plots at some ten co-operating experiment they arose through fertilization of a sexual 
stations in the United States. The actual Fi hybrid by pollen of P. pratensis alpigena 
planting of these tests will not be under originally from Lapland, which was grow- 
way until the fall and spring of 1954-1955 ing in an adjacent plot at Pullman. The 
because the necessary seed will not be selection of these new stabilized strains at 
available until then. During the current Pullman in a combination formerly con- 
year fairly extensive new plantings of sta- sidered to be wholly unsuccessful in this 
bilized hybrid lines have been made by environment is a spectacular demonstration 
the Soil Conservation Service at their nurs- of the possibility for successful selection 
eries at Pullman and Pleasanton, from among open-pollinated progenies of hybrid 
which seed may be available for such tests combinations that initially appear to be 
as are being projected by the U. S. Bureau unpromising, 
of Plant Industry. Especially gratifying is the stabilization 

New data regarding the performance of an apomictic line of Poa ampla X P. 
of existing strains have been obtained at compressa this year at Pullman after re- 
the Soil Conservation Service nurseries at peated failures in previous years. This 
San Fernando and Pleasanton in Cali- demonstrates that it is possible to combine 
fornia, and at Bellingham and Pullman in the genomes of these contrasting species 
Washington, in addition to new informa- into new apomictic lines once the proper 
tion from the plantings at the Stanford, genie balance is achieved. The new hybrid 
Mather, and Timberline transplant stations is vigorous at Pullman and has promising 
maintained by the Carnegie Institution, characteristics, but further testing will be 
Several new apomictic lines of Poa ampla required before its possible agronomic 
X P. pratensis have been stabilized at the value can be determined. Another new 
Pullman nursery of the Soil Conservation stabilized apomict was obtained from the 
Service. These and the ones obtained in same F 3 progeny which evidently is the 
1952 are F 2 lines that are definitely superior product of an open-pollinated outcross be- 
to earlier lines of the same interspecific tween an F 2 hybrid of P. ampla X P. corn- 
cross, being more leafy and more vigorous pressa and an adjacent culture of ampla- 
in growth. These new types include some alpigena. The new derivative is a vigorous 
of our most promising new hybrid lines. strain that combines characteristics of the 

Among the new apomictic lines obtained three species, P. ampla, P. compressa, and 

at Pullman are two constant derivatives of P. pratensis alpigena. 



DEPARTMENT OF PLANT BIOLOGY 



173 



The improvement in quality of new 
apomictic lines of hybrid Poas throughout 
the years is clearly evident at the Pullman 
nursery of the Soil Conservation Service, 
where the 1948, 1949, 1950, 1951, and 1952 
plantings could be compared directly dur- 
ing the current year. The extensive data 
that have been recorded in successive years 
from the same cultures make possible a 
fairly accurate evaluation of the merits of 
these strains in the Pullman environment. 
It is evident that only a small fraction of 
the possibilities for selection among the 



Cytology of Poa Hybrids 

Edward L. Triplett 

A basic step in the analysis of the cytol- 
ogy of Poa hybrids is the determination of 
their chromosome numbers, and most of 
the effort during the current year has been 
devoted to such a study of the hybrids re- 
sulting from the 1951 crossings. The plants 
which have been investigated fall into three 
groups: (1) hybrids involving Poa arida, 

(2) hybrids involving P. arachnifera, and 

(3) quadruple hybrids involving three or 
four species. 



TABLE 5 

Somatic chromosome numbers in parents and interspecific F x hybrids of Poa 



Culture no. 



Combination 



Parents, 2w = 



Fi hybrid individuals, 2n — 



6298 



P. arida X ampla 



6299.... P. arida X ampla 

6271 ... . P. scabrella X arachnifera 

6272. ... P. arachnifera X pratensis 



63, 56 95, 94, 92, 92, 92, 91, 91, 90, 90, 89, 89, 

88, 86, 85, 77, 64 
63, 56 99, 96, 92, 91, 90, 90, 90 

84, 56 75, 75, 74, 73, 72, 70, 69 

56, 68 65, 64, 63, 61, 61, 61, 61, ca. 54 



possible hybrids in Poa have been realized 
during the ten-year period since the Poa 
breeding program was begun, and that it 
should be possible to produce apomictic 
strains of Poa having almost any combina- 
tion of characteristics found among the 
component species of the genus. 

Current studies on the new Poa hybrids 
reported in Year Book No. 51 (1951-1952), 
pages 111-117, that are the result of the 
1951 crossings indicate that many of the 
new combinations are of evolutionary as 
well as of possible agronomic interest, but 
the data are still too incomplete to warrant 
a detailed description of them. Cloned 
individuals of these hybrids and their par- 
ents are now being established at the three 
transplant stations, and they have also been 
the subject of studies on chromosome num- 
bers reported below by Triplett. 



Poa arida-ampla combinations. Two 
plants of Poa arida, both originally from 
North Platte, Nebraska, and having 2/2 = 63 
chromosomes, were pollinated by an indi- 
vidual of P. ampla from Albion, Washing- 
ton, having 2/2=56 chromosomes. The 
hybrids are intermediate between the par- 
ents in morphology and are vigorous when 
grown at Stanford. The chromosome 
numbers indicate that 21 of a sample of 
23 Fi plants of this combination were the 
result of the union of an unreduced female 
gamete and a reduced male gamete, as 
shown in table 5. Two individuals devi- 
ated from the usual range of 2/2 = 88 to 
92 chromosomes in having only 64 and 
77, and probably were the product of 
haploid or hyperhaploid gametes from 
both parents. 

Poa arachnifera combinations. A plant 



174 



CARNEGIE INSTITUTION OF WASHINGTON 



of Poa scabrella originally from Watson- 
ville, California was pollinated by P. arach- 
nifera (272 = 56) from Stillwater, Okla- 
homa. The chromosome number of the 
scabrella parent is yet undetermined but 
was probably 84, the normal number for 
this species. Seven of the Fi hybrids 
ranged in chromosome number from 272 = 
69 to 75 (table 5) . These hybrids are sum- 
mer-active at Stanford, have short rhi- 
zomes, and combine the characteristics of 
the parent species. 



hybrids segregate widely. Evolutionary 
they are of considerable interest, and some 
appear to have highly desirable agronomic 
characteristics. Their chromosome num- 
bers in connection with their morphology 
provide some basis for deductions regard- 
ing the possible genome composition of 
these new derivatives. The chromosome 
numbers of the original grandparental spe- 
cies, the apomictic hybrid parent lines, and 
a sample of their quadruple hybrid off- 
spring are listed in table 6. The largest 



TABLE 6 

Somatic chromosome numbers in quadruple hybrid combinations of Poa 



Culture 
no. 



Combination 



Grandparents, 

2w = 



Fi parents, 
2w = 



Quadruple hybrid 
individuals, 

2n = 



6301. ... P. arida-ampla X ampla-alpigena 63, 63, 70, 74 94, 73 

6302. ... P. ampla-alpigena X arida-ampla 70, 74, 63, 63 73, 94 

6303. ... P. arida-ampla X ampla-pratensis 63, 63, 63, 68 94, 95 

6310. .. . P. scabrella-pratensis X ampla-alpigena 84, 68, 70, 74 75, 73 



99, 85, 69, 65, 64 

95,91 

87, 83, 80 

82, 80, 75, 73, 73, 
72,71,71,71,71, 
71, 69, 69, 68, 66, 
66, 64, 64, 63, 63, 
63, 62, 56 



The same plant of P. arachnifera was 
also pollinated by a plant of P. pratensis 
from Mather, California, having 272 = 68 
chromosomes. Eight Fi plants, all morpho- 
logically indistinguishable from P. arach- 
nifera, were vigorous at Stanford. One had 
the chromosome number 272 = 54 anQl was 
probably not a hybrid, but the other seven 
ranged from 272 = 61 to 65, as shown in 
table 5, and are apparently the product of 
essentially haploid ovules combined with 
haploid pollen. 

Quadruple hybrids. The quadruple com- 
binations studied included the following: 

(1) Poa arida-ampla X ampla-alpigena, 

(2) Poa ampla-alpigena X arida-ampla, 

(3) Poa arida-ampla X ampla-pratensis, 
and (4) Poa scabrella-pratensis X ampla- 
alpigena. Progeny from these quadruple 



sample is of 6310, a combination of ampla- 
alpigena and scabrella-pratensis. It is ob- 
vious from the sample of 23 plants that the 
hybrids were produced from gametes hav- 
ing reduced chromosome numbers. The 
chromosomes in this remarkable quad- 
ruple hybrid combine four very contrasting 
species from highly contrasting environ- 
ments, but range only between 272 = 56 and 
272 = 82 with frequency peaks at 272 = 62-64 
and 71-73. 

Genetic Studies on Ecological Races 

Malcolm A. Nobs, Jens Clausen, and 
William M. Hiesey 

Studies directed toward extending our 
knowledge of the genetic structure of eco- 
logical races belonging to the same or 



DEPARTMENT OF PLANT BIOLOGY x ^ 

closely related species are being pursued segregate widely in the F 2 . Although 

on a broad and systematic basis. They are morphologically very distinct, these two 

directed along two major lines, aimed at species behave biologically as ecological 

the analysis of the genetic structure of races of one species. Some transplants of 

climatic races (i) on a diploid and (2) parents and hybrids were brought from 

on a polyploid chromosome level. Stanford to Mather in April 1953, during 

On the diploid level the genetic differ- a period of frost and snow, and were found 
ences are basic, and although they are far to differ greatly in their degree of frost 
from simple in diploid races of wild plants, resistance; cardinalis was highly susceptible 
they are less complex than in polyploids, to frost injury, but the hybrids were far 
Studies on diploids, therefore, hold some more resistant. Differences in rate of 
promise of ultimate success in a genetic growth of seedling plants at different tem- 
analysis designed to reveal the actions and peratures were also observed between the 
interactions of specific genes. The studies parents and the hybrids: cardinalis seed- 
on alpine and lowland races of Potentilla lings were favored in growth by warm 
glandulosa mentioned in earlier Year days, Lewisii by cool days, and the Fi 
Books fall into this category. The yet un- hybrids by both. These characteristics, 
published results of the genetic analysis of coupled with an array of striking mor- 
these races reveal the action of intricate phological differences among the hybrids, 
systems of balances governed by series of make this group of plants particularly in- 
genes that determine typical character dif- teresting for study of the mode of inherit- 
ferences between the races. The races of ance of morphological and physiological 
P. glandulosa have many features useful differences between ecologically distinct 
for genetic analysis, but they are slow in races. One special use of these plants being 
growth and development. contemplated is in connection with the 

A highly promising group of hybrids physiological studies on climatic races men- 
having most of the advantages of Poten- tioned in later paragraphs of this report. In 
tilla glandulosa and being faster in develop- addition to crosses in the Mimulus cardi- 
ment has been found in the Mimulus cardi- nalis-Lewisii complex, parallel crossings 
nalis-Lewisii complex. The first hybrids are being tried between contrasting races 
between M. cardinalis, a vigorous, red- and species in the M. guttatus complex, 
flowered perennial herb of low altitudes, which, from Vickery's earlier work, were 
and M. Lewisii, a pink-flowered herbaceous also shown to have important possibilities 
perennial of high altitudes, were made by for this type of basic investigation. 
Dr. Robert Vickery in the course of his On the polyploid level the genes in mul- 
graduate research (cf. Year Book No. 50, tiple series also tend to be multiplied. The 
1950-1951, p. 119). Additional hybrids, complex mode of inheritance found in 
using strains differing in greater degree diploid Potentilla glandulosa suggests that 
than those used in Vickery's original actual gene analysis in wild polyploid races 
crosses, were made last year and during would be nearly impossible. Nevertheless, 
the summer of 1953. These are being self- although not so clear-cut as studies on the 
pollinated and backcrossed for further ge- diploid level, studies of crossings between 
netic analysis. Both parents and hybrids polyploid races of the same or closely re- 
have n = 8 pairs of chromosomes, and from lated species are essential to the under- 
Vickery's experiments these are known to standing of evolutionary processes because 



176 



CARNEGIE INSTITUTION OF WASHINGTON 



of the frequency of polyploids in both wild 
and cultivated species. The various poly- 
ploid members of the Achillea millefolium 
complex have been extremely useful from 
this point of view. In Year Book No. 51 
(1951-1952), pages 122-124, some of these 
hybrids and their progeny, especially be- 
tween members on the hexaploid level, in- 
cluding A. borealis, were described. Dur- 
ing the current year a number of new Fi 
combinations have been obtained, mostly 
on the tetraploid level between different 
races of A. lanulosa. These hybrids are 
summarized as follows: 

Port Chicago, salt marsh, coastal X Timber- 
line, Sierran subalpine, 10,000 ft altitude 

Port Chicago X Port Orford, Oregon coast 

Dyerville, Redwood region, 250 ft altitude X 
Timberline 

Dyerville X Big Horn Lake, Sierran alpine, 
11,700 ft altitude 

Dyerville X Hoosier Ridge, Rocky Mt. al- 
pine, 11,700 ft altitude 

Port Orford X Timberline 

Port Orford X Big Horn Lake 

Port Orford X Hoosier Ridge 

Of special interest is the hybrid between 
the tall coastal form of A. lanulosa (earlier 
referred to A. puberula Rydbg.) from the 
salt marshes in the vicinity of Port Chicago, 
Contra Costa County, California, and the 
dwarf subalpine race of A. lanulosa ssp. 
alpicola from near Timberline station at 
10,000 feet altitude. This hybrid is being 
self-pollinated to obtain an F 2 population. 
If the progeny from this combination are 
vigorous and show the segregation ex- 
pected, it is planned to utilize the F2 in a 
selection experiment at the Stanford, 
Mather, and Timberline stations for com- 
parison with a similar experiment already 
under way using F 2 progeny of a hybrid 
between contrasting latitudinal forms of 
A. borealis from Kiska Island in the Aleu- 
tian chain and from the San Joaquin Val- 



ley in California, as described in Year Book 
No. 51. 

The new hybrids made this year between 
races of A. lanulosa are of additional in- 
terest in relation to the cytological irregu- 
larities in the lanulosa hybrids, Port Or- 
ford X Big Horn Lake and Port Orford 
X Vera Cruz, reported by Ehrendorfer 
last year (Year Book No. 51, pp. 124-125). 
These irregularities suggest that genetic 
barriers may exist between some races of 
this highly polymorphic tetraploid species. 
The new hybrids should make possible an 
adequate study of this problem. 

To judge from morphological observa- 
tions, it appears that interspecific hybrids 
between races of the hexaploid A. borealis 
and the tetraploid species A. lanulosa made 
by Ehrendorfer last year have also been 
successful, but cytological and genetic con- 
firmation has not yet been obtained. 

Comparative Physiology of Climatic 
Races 

William M. Hiesey and Harold W. Milner 

Natural selection is probably the most 
important force governing the evolution 
of plants. The studies on the genetic struc- 
ture of climatic races of Potentilla reveal 
that both morphological and physiological 
differences are determined by complex 
systems of gene balances. Used in this 
sense, the term "physiological differences" 
refers primarily to observed contrasts in 
rates of growth, seasonal periodicity, frost 
resistance, and survival when clones of in- 
dividuals of each race are exposed to dif- 
ferent environments. Observations on such 
responses are of great value in interpreting 
general relations between plants and their 
environment, but they do not supply the 
information needed to understand the spe- 
cific mechanisms that operate in natural 
selection. The role of differences in phys- 
iological activity as a factor in natural se- 



DEPARTMENT OF PLANT BIOLOGY 



177 



lection is not at all clear. Critical studies 
on the variations in the individual physio- 
logical processes in response to controlled 
variations in environment are needed be- 
fore we can begin to understand the rela- 
tions between physiological processes and 
natural selection. 

Present methods for the measurement of 
such basic physiological processes as photo- 
synthesis and respiration cannot be applied 
directly to the problem at hand. The ex- 
isting methods are neither rapid enough 
nor sufficiently flexible to permit precise 
quantitative observation of the response of 
many individual plants to a wide range of 
controlled variation in each of several en- 
vironmental factors. Variability within lo- 
cal populations, races, and species also 
needs to be taken into account. This neces- 
sitates the study of many individuals, each 
cultivated as a clone, under a wide range 
of controlled environmental factors. 

The work of the past year has been con- 
cerned primarily with the development of 
apparatus with these requirements in mind. 
As was mentioned in Year Book No. 51 
(1951-1952), pages 131-132, emphasis is 
being placed on the study of rates of res- 
piration and photosynthesis under con- 
trolled conditions of temperature, light in- 
tensity, and atmospheric composition, keep- 
ing other external factors constant. Other 
factors may be varied later as they appear 
to be important. 

The apparatus under construction is de- 
signed to determine the rate of consump- 
tion or liberation of carbon dioxide and of 
oxygen by the plant in a recirculating air 
stream in a closed system. Changes in the 
concentration of carbon dioxide and of 
oxygen in the air stream are determined by 
analyzers which, in turn, control pumps 
for injecting or absorbing the proper 
amounts of the respective gases to maintain 
their concentrations within predetermined 



limits. The amount of carbon dioxide or 
oxygen injected or withdrawn is recorded 
automatically. The time lag between 
changes in concentration of carbon dioxide 
or oxygen in the plant chamber and their 
adjustment by the automatic controls is 
estimated at around 2 minutes. The ac- 
curacy of control of the carbon dioxide or 
oxygen concentration in the air stream 
of the apparatus is expected to be approxi- 
mately 1 per cent of the total concentra- 
tion of either gas. 

A sample of the circulating air stream 
in the apparatus is continuously by-passed 
first through the carbon dioxide analyzer 
and then through the oxygen analyzer. 
The carbon dioxide analyzer is of the type 
designed by Dr. Moyer D. Thomas, of the 
American Smelting and Refining Com- 
pany. Dr. Thomas and his associate, Mr. 
James O. Ivie, have been most generous in 
supplying detailed sketches, photographs, 
and verbal information that have been 
invaluable in the construction of the ana- 
lyzer. In the Thomas method the carbon 
dioxide in the air sample is absorbed quan- 
titatively by a standardized solution of 
sodium hydroxide. The conductivity of the 
resulting solution is related quantitatively 
to the carbon dioxide concentration in the 
air sample. Part of the carbon dioxide- 
free air from the analyzer is then passed 
through a Model F-3 Beckman Oxygen 
Analyzer, which measures the concentra- 
tion of oxygen by the paramagnetic 
method developed by Dr. Linus Pauling 
at the California Institute of Technology. 
The concentrations of carbon dioxide and 
oxygen are measured simultaneously and 
continuously. 

The electrical signals from the carbon 
dioxide and oxygen analyzers go to sep- 
arate amplifiers and electronic control de- 
vices developed by Hawk. The electronic 
controls have three functions: first, to ac- 



T yS CARNEGIE INSTITUTION OF WASHINGTON 

tivate the carbon dioxide and oxygen in- plants, their rapid growth, and their ready 
jectors and absorbers; second, to provide increase through clonal division are ad- 
signals to an Esterline-Angus multiple-pen vantages from the standpoint of practical 
on-off recorder; third, to permit spot- experimentation. Their occurrence in 
check readings on a voltmeter of the con- many parts of the world and in different 
centration of either carbon dioxide or kinds of climate indicates that the Lem- 
oxygen. naceae may contain a number of distinct 
Zenith metering pumps, with their on ecological races and species. The biology 
and off times recorded, accurately meas- of the species of this family, however, is 
ure the volume of gas passing through the not sufficiently well known, and some pre- 
injectors and absorbers. Injectors for car- liminary investigations are needed to deter- 
bon dioxide and oxygen introduce the re- mine the suitability of members of this 
quired amounts of these gases directly in- group for physiological studies of the kind 
to the apparatus. Excess carbon dioxide is contemplated. 

absorbed by passing a portion of the air Kruger has made valuable suggestions 
through a solution of sodium hydroxide, in the mechanical design of the apparatus, 
Excess oxygen is removed by injecting and his help in its construction is grate- 
hydrogen into a sample of the air, which fully acknowledged, 
then passes through a Deoxo Gas Purifier, 

where the hydrogen reacts catalytically Ultraviolet Absorption Spectra of Iso- 

with the stoichiometric equivalent of oxy- lated Root-Tip Nuclei 

gen. The temperature and relative humid- p AUL Grun 

itv of the recirculated air are regulated by ~ , , ,. t 

3 , , .. ., . . , One approach to an understanding or 

passage through a cooling coil maintained , " c „ ,. . . , . . x " 

r ° ° ttt r the causes or cell division (mitosis) is to 

at the proper temperature. Water or tran- , , , • i j-n- i 

. , r . , ., . . . study the chemical differences between 

spiration condenses in the coil and is col- n « ,. . , , , , , 

r cells that divide and those that do not. 

lected and measured. A/r u i • n t i i- i • r n 

Morphologically, metabolic nuclei or all 

The completion and testing of the ap- cdls appear tQ be y£ry similar? although 
paratus will require several additional some may be about tQ enter the complex 
months. It will be necessary to adapt the stages of divisiori) and others may never 
apparatus to the study of plants differing divide again> During a year spent in St0 ck- 
in size and structure. Plant materials suit- holm> Sweden, at the laboratory of Profes- 
able for such studies are available in abun- sor x. O. Caspersson, an attempt is being 
dance from the concurrent investigations made to analyze the nucleic acid and pro- 
being conducted in the Department. A tein contents of nuclei of cells still going 
search for other plants even better suited through the mitotic cycle, and of cells in 
to studies of the comparative physiology differentiated, nondividing tissue. This 
of ecologic races is nevertheless being should offer the possibility of comparing 
made. Of interest in this connection are nuclei that have just gone through divi- 
members of the family Lemnaceae, and sion, those about to go through division, 
some exploratory collections of Lemna and and those that would ordinarily never 
Spirodela have already been made. These again divide. 

are among the smallest of the higher plants Growing root tips of Tradescantia palu- 

and have a relatively simple anatomical dosa contain dividing cells in large num- 

structure. The very small size of these bers in a region restricted to within 2.5 mm 



DEPARTMENT OF PLANT BIOLOGY 



179 



from the tip, whereas no divisions occur 
in the following 2.5 mm. The part of the 
root with nondividing cells is derived 
from the mitotic portion with which it is 
to be compared, and so contains cells that 
ceased division in the recent past. A tech- 
nique has been developed for freeing nu- 
clei from cell walls and cytoplasm so that 
they can be subjected to microscopic study 
in an isolated condition. Roots are freeze- 
dried, a process of killing and drying 
thought to leave tissue in a relatively un- 
changed condition with respect to chemical 
content. They are then immersed directly 
in dry glycerine and remain there for at 
least 6 hours. Thereafter root parts still 
in the glycerine are mashed and ground 
with a spear-tipped needle, a process which 
frees many intact nuclei, which float from 
the cell walls and cytoplasm. The mixture 
is then mounted on a quartz slide for 
study. 

The ultraviolet microspectrophotometric 
methods developed by Professor Caspers- 
son are being used to assay the chemical 
content of the isolated nuclei. This method 
involves moving individual nuclei across a 
beam of ultraviolet light using a single 
wave length at a time, and measuring elec- 
tronically the fraction of light of each wave 
length absorbed by the nuclei. The nuclei 
are scanned at wave lengths of 2650, 2750, 
2800, 2900, and 3150 A. It is known that 
nucleic acids (both ribo- and desoxyribo- 
nucleic acid) have an absorption curve 
with a maximum at 2600 A, whereas the 
only two amino acids of importance in 
this connection, tryptophane and tyrosine, 
have absorption maxima at about 2800 A. 
The relative heights of the 2650 and 2800 



A absorptions are, thus, a measure of the 
relative content of nucleic acid and of 
protein; and the absolute heights are a 
measure of the total quantities of these 
absorbing substances present. 

The measured nuclear absorption curves 
usually show a peak at 2650 A, and a hump 
at 2800 A. There is great variation even 
within single tissues in the sizes of the 
nuclei, the heights of the absorption curves, 
and the ratio of 2650 to 2800 A absorption. 
To judge the amounts of nucleic acid and 
amino acid present in the nuclei, it is neces- 
sary to separate the complex absorption 
curves into component parts. The assump- 
tion is made at the start that the proportion 
of tyrosine to tryptophane in the protein 
is the same as that commonly found in 
chemical analyses of plant proteins, 2.7 
parts tyrosine to 1.6 parts tryptophane. 
Curves of the absorption of mixtures of 
different proportions of nucleic acid and 
the amino acids have been calculated to 
fit as closely as possible the observed nu- 
clear absorption. It has been necessary 
also to take into account the fact that the 
position and height of the tyrosine maxi- 
mum varies with the degree of dissocia- 
tion in the molecule. Good fits have been 
obtained between the observed nuclear ab- 
sorption spectra and calculated nucleic 
acid-amino acid absorption spectra when 
calculations were based on 25 per cent dis- 
sociation of the tyrosine. 

Work is now in progress on amassing 
a large enough body of material so that 
the statistical significance of the differences 
between nuclei of these tissues can be 
determined. 



i8o 



CARNEGIE INSTITUTION OF WASHINGTON 



PALEOBOTANY 



Ralph W. Chaney 



During the 1952 field season, plant fos- 
sils were collected at two localities in Ore- 
gon where the mixed deciduous forest of 
the Oligocene epoch is well preserved. 
One of these is at a recently discovered site 
in the John Day Basin, in beds assigned 
on stratigraphic grounds to the Lower 
John Day formation. The second fossil 
flora comes from Rujada in the Willamette 
Valley on the western side of the Cascades; 
stratigraphic relations are here less clear, 
for the plant-bearing sediments are inter- 
bedded in lava flows which may span a 
large segment of the Tertiary period. A 
comparison of the two floras has been 
made by Dr. R. W. Lakhanpal, of the 
Birbal Sahni Memorial Institute of Paleo- 
botany, in the course of a year spent as 
UNESCO fellow at the University of 
California. They are similar in their pre- 
dominance of temperate genera, such as 
Alnus (alder), Quercus (oak), and Plata- 
nus (sycamore), and have many identical 
species in common. But the Rujada flora 
has a more conspicuous element of broad- 
leafed evergreens, which appear to have 
made up an important part of the under- 
story. Another significant difference is the 
rarity of Metasequoia (Chinese redwood) 
at Rujada and the occurrence there of 
Sequoia of the coast redwood type; by 
contrast, Sequoia has not been collected at 
Fossil, where the foliage of Metasequoia 
outnumbers the remains of all the asso- 
ciated trees. It seems apparent that the 
Rujada forest was a coastal assemblage, in 
which marine climate and its lower tem- 
perature range made possible the occur- 
rence of many evergreen plants; by con- 
trast, the Fossil forest, living some hundred 
and fifty miles from the Tertiary shore, 
was largely deciduous and more typically 
temperate. In any such interpretation the 



present-day restriction of Sequoia semper- 
virens to the coastal belt of California and 
Oregon, and the contrasting occurrence of 
Metasequoia glyptostroboides in the in- 
terior valleys of central China, provide the 
basis for an understanding of Oligocene 
forests in which their Tertiary ancestors, 
Sequoia affinis and Metasequoia occiden- 
tals, were dominant trees. Today, with 
the more recently uplifted Cascade Range 
intervening to form a major climatic bar- 
rier, the forests of the Willamette Valley 
and the John Day Basin show even greater 
differences than during the Oligocene. 

Stratigraphic paleontologists have long 
looked for similarities rather than differ- 
ences in determining the age of deposits 
bearing plant and animal fossils. In recent 
years students of fossil invertebrates, es- 
pecially microfossils, have begun to recog- 
nize the significance of facies differences, 
and paleoecology now enters largely into 
their considerations of age. Vertebrate pa- 
leontologists have been somewhat slower 
to recognize the possibility that two unlike 
faunas may have a close age relationship, 
though even in this field of life history 
there is evidence of increasing understand- 
ing of the areal relations of Tertiary mam- 
mals. The combination of similarities and 
dissimilarities in the case of the Rujada 
and Fossil floras, and its bearing on the 
problem of the age of the deposits con- 
taining them, is one of many such cases 
which the study of Tertiary floras in 
western North America has brought to 
light. Having in mind the movements of 
vegetation in response to climatic change 
in later geologic time, it may be said that 
complete similarity of two fossil floras 
from widely separated localities is a chal- 
lenge to any conclusion that they lived 



DEPARTMENT OF PLANT BIOLOGY 



181 



at the same time. In the past, as today, 
there have been widespread contempora- 
neous forests; but any careful analysis of 
the details of their composition is likely to 
show the same sorts of differences, result- 
ing from varying latitude, altitude, and 
distance from the sea, that may be noted 
in comparisons of modern vegetation. 

Using this dynamic approach to the 
problems of age determination, compari- 
sons are now being made between the 
well known floras of the standard section 
in the John Day Basin and recently dis- 
covered floras in western Oregon and 
Washington. The active assistance of Mr. 
Rudolf Erickson and Mrs. Eleanor Gor- 
don, of Portland, both of whom have 



discovered and collected significant plant- 
bearing deposits, along with other mem- 
bers of the Geological Society of the 
Oregon Country, is adding greatly to the 
effectiveness of the study of Tertiary vege- 
tation west of the Cascades. In north- 
western Washington Marie B. Pabst has 
under way a comprehensive program deal- 
ing with the older Tertiary floras there, 
long known but little understood. Her 
detailed study of the ferns of the Chucka- 
nut formation is already adding significant 
evidence regarding the climate and age of 
early Tertiary floras long grouped together 
under the Puget group, and is showing 
that the latter name no longer has either 
stratigraphic or floristic significance. 



BIBLIOGRAPHY 



Chaney, Ralph W. Conifer dominants in the 
middle Tertiary of the John Day Basin, Ore- 
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(1952). 

Davis, Edwin A. Photosynthetic Chlorella mu- 
tants. Amer. Jour. Bot., vol. 39, pp. 535-539 
(1952). 

Jean Dedrick, C. S. French, H. W. 

Milner, Jack Myers, J. H. C. Smith, and 
H. A. Spoehr. Laboratory experiments on 
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of Washington Department of Plant Biology. 
In Carnegie Inst. Wash. Pub. 600, 1 pp. 105- 

153- 
Dedrick, Jean. See Davis, Edwin A. 

French, C. S. See Davis, Edwin A. 

Grant, Verne. Cytogenetics of the hybrid Gilia 
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meiosis and polyploidy rate as affected by 
nutritional and genetic conditions. Chromo- 
soma, vol. 5, pp. 372-390 095 2 )- 

Isolation and hybridization between 

Aquilegia jormosa and A. pubescens. El 
Aliso, vol. 2, pp. 341-360 (1952). 

Genetic and taxonomic studies in Gilia. 

II. Gilia capitata abrotanijolia. El Aliso, 
vol. 2, pp. 361-373 (1952). 

Genetic and taxonomic studies in Gilia. 

III. The Gilia tricolor complex. El Aliso, 
vol. 2, pp. 375-388 (1952). 



Hase, E. See Tamiya, H. 

Hiesey, William M. Growth and development 
of species and hybrids of Poa under con- 
trolled conditions. Amer. Jour. Bot., vol. 40, 
pp. 205-221 (1953). 

Dynamisme de revolution d'apres la 

conception d'un experimentateur. In Col- 
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la Recherche Scientifique sur l'Evolution et 
la Phylogenie chez les Vegetaux, vol. 5, pp. 
C271-C279 (1952). 

See Juhren, Marcella. 



Iwamura, T. See Tamiya, H. 

Juhren, Marcella, William M. Hiesey, and 

F. W. Went. Germination and early growth 

of grasses in controlled conditions. Ecology, 

vol. 34, pp. 288-300 (1953). 
Kok, Bessel. Experiments on photosynthesis by 

Chlorella in flashing light. In Carnegie Inst. 

Wash. Pub. 600, 1 pp. 63-75. 
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In Carnegie Inst. Wash. Pub. 600, 1 pp. 85- 

102. 
and William J. McAleer. Growth and 

evaluation of species of algae with regard 

to sterol content. In Carnegie Inst. Wash. 

Pub. 600, 1 pp. 316-325. 

1 Carnegie Institution of Washington Publication 
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l82 



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Macdowall, F. D. H. The reducing potential 
of illuminated chloroplasts. Science, vol. 116, 

PP- 398-399 (1952). 
MacGinitie, Harry D. Fossil plants of the 

Florissant beds, Colorado. (Contributions to 

Paleontology.) Carnegie Inst. Wash. Pub. 

599. iii + 198 pp. (1953). 
McAleer, William J. See Krauss, Robert W. 
Milner, Harold W. Chlorella as a source of 

proteins and fats: Laboratory to pilot plant 

experiments. The Vortex, vol. 13, pp. 368— 

380 (1952). 

The chemical composition of algae. In 

Carnegie Inst. Wash. Pub. 600, 1 pp. 285-302. 

See Davis, Edwin A. 



Mituya, A., T. Nyunoya, and H. Tamiya. Pre- 
pilot-plant experiments on algal mass culture. 
In Carnegie Inst. Wash. Pub. 600, 1 pp. 273- 
281. 

See Tamiya, H. 

Myers, Jack. The biology of the algae: A brief 
summary. In Carnegie Inst. Wash. Pub. 600, 1 
PP- 31-36. 

. Growth characteristics of algae in rela- 
tion to the problems of mass culture. In 
Carnegie Inst. Wash. Pub. 600, 1 pp. 37-54. 

See Davis, Edwin A.; Sorokin, Con- 



STANTINE. 

Nihei, T. See Tamiya, H. 
Nyunoya, T. See Mituya, A. 
Sasa, T. See Tamiya, H. 



Shibata, K. See Tamiya, H. 

Smith, J. H. C. See Davis, Edwin A. 

Sorokin, Constantine, and Jack Myers. A 
high-temperature strain of Chlorella. Sci- 
ence, vol. 117, pp. 330-331 (1953). 

Spoehr, H. A. English summary of "StofTpro- 
duktion durch Griinalgen und Diatomeen in 
Massenkultur," by H. von Witsch and R. 
Harder. In Carnegie Inst. Wash. Pub. 600, 1 
pp. 164-165. 

The need for a new source of food. In 

Carnegie Inst. Wash. Pub. 600, 1 pp. 24-28. 

Society in the grip of science. Address 

of retiring president, Pacific Division, 
A. A. A. S. Published by the author. 16 pp. 
(1952). 

A new look at the food problem. Gar- 
den Jour. New York Bot. Garden, vol. 2, pp. 
133, 134, 153, 156 (1952). 

See Davis, Edwin A. 



Tamiya, H., E. Hase, K. Shibata, A. Mituya, 
T. Iwamura, T. Nihei, and T. Sasa. Kinetics 
of growth of Chlorella, with special refer- 
ence to its dependence on quantity of avail- 
able light and on temperature. In Carnegie 
Inst. Wash. Pub. 600, 1 pp. 204-232. 

See Mituya, A. 

Went, F. W. See Juhren, Marcella. 

1 Carnegie Institution of Washington Publication 
600. Algal culture: From laboratory to pilot plant. 
Editor, John S. Burlew. ix + 357 PP- (i953)- 



DEPARTMENT OF EMBRYOLOGY 

Baltimore, Maryland 
GEORGE W. CORNER, Director 

During the past year the staff of the De- ence will increase the competence of the 
partment of Embryology, augmented by Department to deal with the biochemical 
one major appointment, has maintained its problems, now pressing for solution, of the 
program of research and publication at full living egg and embryo and the female re- 
tide. The only serious problem has been productive system. 

to find room for all the workers and for Dr. Beni Horvath, formerly Fellow of 

the numerous visitors who come from all Columbia University, College of Physi- 

parts of the world to avail themselves of cians and Surgeons, joined the Department 

the collections and experimental facilities. July i, 1952, on a fellowship of the Car- 

Dr. David W. Bishop became a member negie Institution, as a member of the 
of the Department October 1, 1952. A group working with Dr. Csapo on the bio- 
graduate of Swarthmore College and of chemistry of uterine muscle, 
the University of Pennsylvania (Ph.D. Dr. Brenda M. Schofield came in Janu- 
1942), he was with the U. S. Fish and ary 1953 from the Department of Pharma- 
Wildlife Service (1941-1942) and the cology of Oxford University, England, on 
Army Air Force Physiology Program a Fulbright Fellowship. 
(1942-1946). After holding academic posi- Dr. Ronald Singer completed in Septem- 
tions at the University of Colorado and the Der 1952 his term as Fellow of the Interna- 
University of Illinois, he became professor t i ona i R ota ry Foundation, and returned to 
of physiology at the University of Massa- n i s post at the University of Cape Town, 
chusetts (1948-1951). In 1951-1952 he held Soutn Africa. 

a fellowship of the Planned Parenthood Dr Vittorio Danesino, Department of 

Foundation, working at the California In- Gynecology and Obstetrics, University of 

stitute of Technology. His researches have Naples, began in April 1953 a stay of a 

dealt chiefly with the physiology and bio- year as a Fulbright Fellow, during which 

chemistry of sperm cells, with special refer- ne wi n_ wor k i n association with Dr. Bar- 

ence to oxygen utilization and enzymatic telmez, Dr. Bishop, and Dr. Reynolds, and 

activities. The methods used in this kind a l so i n tne Department of Obstetrics, Johns 

of research will ultimately be useful also Hopkins Hospital. 

in analyzing similar vital activities of the Dr. Chester H. Heuser, Research Asso- 

early embryo and of its uterine environ- c i ate) aga i n S p en t several weeks at the labo- 

ment. Like the sperm cells, the fertilized ratory, in the summer of 1952, continuing 

eggs and early embryos of mammals live his work on very early embryos, 

for a time free in the reproductive tract, Dr. E. Carl Sensenig returned for ten 

depending on their internal resources to weeks in the summer of 1952 to continue 

utilize oxygen and nutritive substances fur- investigations on the development of the 

nished by the surrounding tissues of the spinal column in human embryos. At the 

mother. It is expected that as Dr. Bishop University of Alabama he has prepared 

follows out his well developed program of about twenty human fetuses put at his dis- 

research on the male germ cells, his experi- posal on loan, for study of the later stages 

183 



i8 4 



CARNEGIE INSTITUTION OF WASHINGTON 



of normal and abnormal development of Dr. R. Licata, University of Michigan, 

the spine. July-August 1952: development of coro- 

Commander Roy E. Crowder, Medical nary vessels. 

Corps, U. S. Navy, again devoted two Dr. Eileen Otis, University of Rochester, 

weeks of his leave (December 1952) to re- October-November 1952: variability of rate 

search on the development of the human of development of human embryos, 

adrenal gland. Dr. Bradley M. Patten, University of 

Dr. Perry W. Gilbert, of Cornell Uni- Michigan, February 1953: study of human 

versity, made two visits of a few days each embryos. 

to work on the illustrations of his forth- Dr. C. A. Salvatore, University of Sao 

coming monograph on the development of Paulo, Brazil, October 1952: to observe the 

the external muscles of the human eye. program of investigations. 

The following persons also visited the Dr. Luis Vargas, Catholic University of 

laboratory, making use of the collection of Santiago, Chile, March 1953: to observe the 

human and other primate embryos, for program of investigations, 

study of the topics indicated: Absence of Director. The Director was 

Dr. James K. Avery, University of Roch- abroad most of the year, having been 

ester, January 1953: development of the gran ted leave of absence from September 

teeth. 1, 1952 in order that he might accept an in- 

Dr. Elio Borghese, University of Pavia, vitation to serve as George Eastman Visit- 
Italy, September-November 1952: early ing Professor at the University of Oxford 
human embryos. for the academic year 1952-1953. 

Dr. Gordon W. Douglas, New York When informing Dr. Corner of this ac- 

University, May 1953: development of tion of the Trustees, Dr. Bush emphasized 

mammalian embryos to trophoblast stage, their earnest wish to contribute in every 

Dr. Kenneth B. Duke, Duke University, possible way to Anglo-American co-opera- 
June 1953 : study of primate embryos in the tion in science. At Oxford Dr. Corner 
Bluntschli Collection. received a warm welcome and generous 

Dr. A. M. Elshout, New York Univer- courtesy at all times from the University 

sity, May-June 1953 : modeling techniques, officials, from the Department of Anatomy, 

Dr. H. Goldberg, Johns Hopkins Hospi- and from Balliol College, to which he was 

tal : frozen-section technique. attached as Fellow for the year. 

Dr. Hugh G. Grady, Armed Forces In- Dr. Samuel R. M. Reynolds served as 

stitute of Pathology, July 1952: human Acting Director during this period, 

trophoblast and decidua. Academic honors. Dr. Robert K. Burns 

Dr. Robert C. Hardy, New York Hospi- received the honorary degree of Doctor of 

tal, July 1953 : study of embryos with hare- Science from his alma mater, Bridgewater 

lip. College, June 1, 1953. 

Dr. Miriam Kelner, University of Re- Dr. Arthur T. Hertig, Research Associ- 

cife, Brazil, December 1952: study of hu- ate, was appointed Shattuck Professor of 

man embryos. Pathological Anatomy and Head of the 

Dr. E. Levy, Morrisania Hospital, New Department of Pathology, Harvard Uni- 

York, April-August 1953: development of versity, beginning with the autumn term 

pelvic floor and anal region. of 1952. 



DEPARTMENT OF EMBRYOLOGY 



185 



Lewis H. Weed 

The death of Dr. Lewis H. Weed in De- 
cember 1952 is appropriately recorded by 
the President elsewhere in this Year Book. 
The Department of Embryology, however, 
has special reason to mourn his loss, for in 
various ways he was associated with it for 
thirty-five years. One of his earliest scien- 
tific papers — in the long run perhaps the 
most valuable of all his contributions — the 
monograph on The Development of the 
Cerebro-Spinal Spaces in Pig and Man, 
beautifully illustrated by James F. Didusch, 
was published in 1917 as volume 5 of the 
Contributions to Embryology. Two sub- 
sequent articles appeared in volumes 9 
(1920) and 17 (1926). From 1922 to 1935 
Dr. Weed, who was during those years 
professor of anatomy in the Johns Hopkins 
University, was also a Research Associate 
of the Carnegie Institution, receiving an 
annual grant for technical assistance in his 
valuable researches on the cerebrospinal 
fluid and related subjects. As a Trustee of 
the Institution from 1935 until his death, 
he was in a favorable position, in the most 
literal sense, to keep an eye on the Depart- 
ment of Embryology from his own office 
next door, in the Johns Hopkins Depart- 
ment of Anatomy. Dr. Weed was associ- 
ated with the founder and first director of 
the Department of Embryology, Professor 
Franklin P. Mall, as a student and later as 
a member of Mall's staff in the Medical 
School. He was the closest scientific neigh- 
bor and friend of the second director, Dr. 
George L. Streeter, during the whole of his 
term of office. To the present incumbent, 
particularly during the earlier years of his 
service, before duties at the National Re- 
search Council began to keep Dr. Weed at 
Washington most of the time, the latter 
was particularly helpful, combining per- 
sonal friendship with ever wise and dis- 
creet advice. 



Contributions to Embryology, 
Volume 35 

At the time of this report, volume 35 of 
the Contributions to Embryology is in 
preparation. Publication is expected in 
1954. The volume will contain the follow- 
ing articles: 

231. George W. Corner and George W. 
Bartelmez, Early abnormal embryos of the 
rhesus mon\ey. 

232. Christine Gilbert and Chester H. 
Heuser, Studies in the development of the 
baboon {Papio ursinus). A description of 
two presomite and two late somite stage em- 
bryos. 

233. G. W. Bartelmez, with the collabora- 
tion of Mary P. Blount, The formation of 
neural crest from the primary optic vesicle in 
man. 

234. S. R. M. Reynolds, G. M. Ardran, and 
M. M. L. Prichard, Observations on regional 
circulation times in the lamb under fetal and 
neonatal conditions. 

235. L. J. Wells and G. van Wagenen, 
Androgen-induced female pseudohermaphro- 
ditism in the mon\ey (Macaca mulatto): 
Anatomy of the reproductive organs. 

236. L. J. Wells, Development of the hu- 
man diaphragm and pleural sacs. 

237. Anna W. Chacko and S. R. M. Reyn- 
olds, Architecture of distended and nondis- 
tended human umbilical cord tissues, with 
special reference to the arteries and veins. 

238. Elizabeth Mapelsden Ramsey, Venous 
drainage of the placenta of the rhesus mon\ey 
{Macaca mulatto). 

239. Theodore W. Torrey, The early de- 
velopment of the human nephros. 

240. Arthur T. Hertig, John Rock, Eleanor 
C. Adams, and William J. Mulligan, On the 
preim plantation stages of the human ovum: 
A description of four normal and four ab- 
normal specimens ranging from the second 
to the fifth day of development. 

241. George W. Settle, Localization of 
the erythrocyte-forming areas in the early 
chic\ blastoderm cultivated in vitro. 



i86 



CARNEGIE INSTITUTION OF WASHINGTON 



RESEARCH IN PROGRESS 



Embryo, Fetus, Uterus 

Early human embryos. Dr. Chester H. 
Heuser, Research Associate, continued his 
work on the earliest embryos of the Car- 
negie Collection, that is to say those of 
groups i to v of the Streeter classification. 
He has made reconstructions of several 
early embryos of groups vi and viii. Dr. 
Heuser plans to prepare monographs of 
these stages which will form a companion 
volume to that of Dr. Streeter (see Year 
Book No. 51, 1951-1952, p. 168), this being 
the period of development that was not yet 
covered at the time of Dr. Streeter's death. 
Dr. Heuser has added three excellent em- 
bryos of horizon viii (about 17 days old) 
to the collection. Two of these (nos. 9009A, 
B) are identical twins, by far the earliest 
human specimens of twinning yet seen. 
The case is especially valuable because it 
gives indisputable proof that uniovular 
twinning can actually occur in one of the 
ways that have been postulated from the 
evidence of later stages, namely by forma- 
tion, inside a single blastocyst, of two em- 
bryonic areas, each of which becomes a 
separate embryo. 

Dr. Arthur T. Hertig, Research Associ- 
ate, reports that during the year five hu- 
man uteri, thought likely to contain very 
early embryos, were searched without suc- 
cess. Several excellent embryos of later 
stages were sent to Baltimore for the de- 
partmental collection. Dr. Hertig and his 
associates in Boston are working on a 
micro-biochemical study of enzymes, inor- 
ganic iron, and calcium in human embryos. 
This work, supported by the Carnegie In- 
stitution only in so far as the Institution's 
grant on behalf of the search for early em- 
bryos facilitates also the collection of later 
stages which can be utilized for the chemi- 
cal study, is of course closely relevant to 
the Department's general program. An in- 



teresting detail of the findings, some of 
which are in press at the time of this re- 
port, is that the primary germ cells (cf . the 
account of these cells by Dr. Emil Witschi 
in Contrib. to Embryol., vol. 32, pp. 67-80) 
exhibit a high alkaline phosphatase activity 
which sharply contrasts them with the sur- 
rounding tissues. 

Extrinsic muscles of the eye. Dr. Perry 
W. Gilbert, of Cornell University, whose 
frequent visits to the laboratory following 
a long stay some years ago have been men- 
tioned in these reports, has made consider- 
able progress on his monograph on the ori- 
gin and development of the human extrin- 
sic eye muscles. Illustrations are now being 
prepared by James F. Didusch. This is ex- 
pected to be a definitive work, presenting 
for the first time an exhaustive account of 
a very important subject about which prac- 
tically nothing appears in the literature of 
human embryology. Dr. Gilbert's unex- 
pected demonstration of "head cavities" in 
human embryos (Year Book No. 50, 1950- 
1951, p. 143) calls for renewed attention to 
lower mammals. Head cavities have been 
seen in a number of marsupials, but oddly 
enough not in the North American opos- 
sum (Didelphys virginiand) , which is one 
of the most primitive of the marsupials. 
Applying the experience gained from his 
previous work to specimens belonging to 
Dr. C. H. Heuser and to the Wistar Insti- 
tute of Anatomy and Biology, Dr. Gilbert 
has now found head cavities in opossum 
embryos of the 10th to 12th days of gesta- 
tion (McCrady's stages 28 to 32). As in 
other vertebrates in which head cavities ap- 
pear, they are obliterated by the primor- 
dial eye-muscle tissue which develops about 
them. 

Effects of rubella {German measles). 
As previously reported, the Collection now 
contains several human fetuses (8 at the 



DEPARTMENT OF EMBRYOLOGY 



187 



time of writing) that were aborted by phy- 
sicians because the mothers had contracted 
German measles during the first trimes- 
ter of pregnancy. The fetuses in utero 
therefore had become liable (according to 
clinical experience) to severe injury to the 
eyes, ears, or heart. Any information bear- 
ing on the nature of this injury, on the 
time in prenatal life at which it becomes 
visible, and on the frequency with which 
it is to be expected will be of great use to 
physicians who have the grave responsi- 
bility of advising a course of action when 
a pregnant woman is affected by this other- 
wise innocuous disease. Dr. G. W. Bartel- 
mez is therefore continuing intensive study 
of our specimens, all of which have been 
serially sectioned. Thus far very little evi- 
dence of damage has been found. One of 
the specimens shows possible injury to the 
lenses of the eye, but this must be checked 
against a control specimen of the same age 
prepared with the same fixative. Such a 
specimen is not yet at hand. 

Blood vessels of the endometrium. The 
blood vessels of the lining of the uterus, in 
man and rhesus monkey, are known to un- 
dergo periodic structural changes related to 
the menstrual cycle. Dr. Bartelmez is 
making a detailed study of these changes, 
using the extensive rhesus monkey mate- 
rial available in the laboratory (Bartelmez- 
Van Dyke, Hartman, Corner collections). 
He finds that differences between speci- 
mens of the same stage of the cycle are 
more obvious in the vessels than in glands 
and stroma, and believes that the distinc- 
tive reactions of the four zones of the 
endometrium are correlated with these 
differences. 

Umbilical cord. In connection with the 
physiological studies of Dr. Reynolds on 
the blood flow through the umbilical cord, 
it became necessary to know something 
about the nerve supply of the umbilical 



blood vessels. Dr. Bartelmez has been ap- 
plying his expert knowledge of neurology 
to the elucidation of this problem. Dr. Vit- 
torio Danesino is aiding in this study. 

Nerves of the uterus. Dr. G. W. Corner, 
while at Oxford, joined with Dr. Graham 
Weddell, lecturer in anatomy there, and 
Dr. Wazir Pallie, a postgraduate student, 
in a study of the intrinsic nerves of the 
uterus. It has long been known that the 
motility of the organ is largely automatic, 
and yet is influenced by factors that seem 
to operate through the nervous system. In 
experimental animals, stimulation of the 
sympathetic nerves causes the uterine mus- 
cle to contract. On the other hand, recent 
investigations by Dr. Csapo and other 
members of this Department have empha- 
sized the independent contractility of uter- 
ine muscles and have shown that such con- 
trol as the body has over it is largely 
exerted by the ovarian hormones. It there- 
fore becomes necessary to learn as much 
as possible about the nerve supply of the 
uterus, in order to understand what part it 
plays in uterine function. The study made 
at Oxford, which utilized the most recent 
improvements in intra-vitam staining of 
nerves, developed by Dr. Weddell and his 
associates, showed that the innervation of 
the myometrium is of very simple, gener- 
alized nature, resembling that of the blood 
vessels. An illustrated report is being pre- 
pared for publication. 

Placenta. Thanks to the co-operation of 
our obstetrical colleagues at the Johns Hop- 
kins, Sinai, and Lutheran Hospitals, of 
Baltimore, Dr. Elizabeth M. Ramsey now 
has at her disposal a collection, remarkable 
for extent and excellence, of 12 human 
placentas in situ in the uterus, from all 
three trimesters of pregnancy, in which 
the fetal blood vessels have been injected. 
Work on the analysis of the placental cir- 
culation in these specimens is actively in 



i88 



CARNEGIE INSTITUTION OF WASHINGTON 



progress, with particular reference to the 
much-discussed Spanner theory of exclu- 
sive marginal drainage. Dr. Ramsey's thor- 
ough study of this question in the rhesus 
monkey is now in press (Contributions to 
Embryology) . 

Pathology of the embryo and fetus. Dr. 
Ramsey examined during the year 90 speci- 
mens sent from eight states. Reports on all 
these were sent to the physicians and insti- 
tutions from which they came. Dr. G. W. 
Bartelmez acted as consultant in some of 
these cases. This routine task is consid- 
ered worth the effort of a research labora- 
tory, not only as a public service, but also 
because it suggests problems and from 
time to time yields valuable material for 
study. Another activity of Dr. Ramsey in 
this same field will receive mention below 
under "Co-operative Research Activities." 

Experimental Embryology 

Recent progress made by Dr. R. K. 
Burns in elucidating the effects of sex- 
gland hormones on the embryonic urino- 
genital system was fully discussed in Year 
Book No. 51 (1951-1952), pages 170-171. 
During the past year Dr. Burns has pur- 
sued this important line of investigation 
with particular reference to the effects 
(discovered by him) of the sex-gland hor- 
mones on the differentiation of the testis, 
and to the reaction of the interstitial tissue 
of the opossum testis to these hormones. 

Physiology of implantation. As has pre- 
viously been reported, Dr. Bent G. Boving 
is investigating the mechanisms by which 
the mammalian embryo becomes attached 
and implanted in the uterus. He has found 
that, in the rabbit, there are three phases, 

(1) a muscular grasping by the uterus, 

(2) an adhesion to the uterus, and (3) the 
long-recognized implantation by groups of 
embryonic trophoblast cells which invade 
the uterus. 



At the time of attachment, the products 
of conception have developed into a blasto- 
cyst, that is, a hollow sphere of cells with 
a clump of cells, the future embryo proper, 
at one pole. The blastocysts have enlarged 
and have reached a stage at which they 
are no longer moved longitudinally in the 
cylindrical uterus, but are accommodated 
by local ballooning out of the uterine wall 
on the free side, opposite the uterine liga- 
ment or mesometrium. This forms a 
"dome" for each blastocyst. Dr. Boving 
has conducted numerous experiments 
aimed at understanding the mechanism 
and function of dome formation. Sus- 
pected mechanical and chemical stimuli 
were imitated by distending the uterus 
with plastic beads of various sizes, and 
with similar beads the perforations of 
which had been loaded with alkali. He 
also measured the pressures needed to 
make the uterus balloon out when dis- 
tended by solutions of various degrees of 
alkalinity. These experiments, which are 
of preliminary nature, will be continued. 
Dome function was studied by observa- 
tions and manipulations of blastocysts 
within the living uterus. Each blastocyst 
was discovered to be held in its dome by 
a muscular grasp which could be released 
by injecting fluid until the uterus became 
distended. 

Similar procedure was found not to re- 
lease blastocysts that were slightly more 
advanced; they had become adherent to 
the uterus. This attachment consistently 
begins in a part of the blastocyst opposite 
the embryonic rudiment, and it is accom- 
panied by localized physical changes, in- 
cluding the development of adhesiveness, 
in the membranes surrounding the blasto- 
cyst. Dr. Boving discovered that a corre- 
sponding area shows a well defined alka- 
line reaction in blastocysts removed from 
the uterus and placed in appropriate test 



DEPARTMENT OF EMBRYOLOGY 



189 



solutions. In the same region, by simply 
drying a blastocyst on a glass slide, he 
found crystals resembling sodium bicar- 
bonate. The alkaline blastocyst substance 
has a titration curve which resembles that 
of sodium bicarbonate solution and shares 
with it an increase of alkalinity on ex- 
posure to air (presumably through a loss 
of carbon dioxide) and a decrease of alka- 
linity when expired air is blown through 
the solution. 

Dr. Boving has also given much thought 
to the factors which determine the direc- 
tion of growth of the trophoblastic proces- 
ses as they sprout from the blastocyst wall 
and invade the uterus during implantation. 
His reconstruction and statistical analysis 
of the pattern of growth indicates that in- 
vasion is directed toward individual blood 
vessels immediately underneath the uterine 
epithelium. The guiding influence is al- 
most certainly a chemical substance ema- 
nating from the vessels. It is conceivable 
that removal of carbon dioxide through 
the vessels could produce an appropriately 
localized alkalinity and adhesiveness of 
trophoblast cells preceding actual invasion, 
but the pattern of invading cell groups 
suggests that the actual penetration of the 
uterine epithelium covering the vessels 
probably does not result from a direct ac- 
tion on embryonic tissue by blood-borne 
oxygen, acidity regulators, or enzymes, and 
is presumably dependent on an indirect 
action such as hormone-induced activity of 
the uterine epithelium. 

Fetal Physiology 

Shortening of blood vessels. In a study 
completed last year by Dr. S. R. M. Reyn- 
olds and Dr. Anna W. Chacko but not 
yet published, the architecture of umbilical 
arteries and veins in the normally dis- 
tended state was described. One of the 
observations was that the degree of thick- 



ening of the wall of an artery when empty 
and constricted is such that it can be ex- 
plained only by assuming concomitant 
shortening and narrowing of the vessel. 
The shortening was calculated to be of the 
order of 17 per cent. This is made possible 
by the double (clockwise and counter- 
clockwise) spiraling of the muscular com- 
ponents and the longitudinal arrangement 
of elastic tissue in a distended, functioning 
vessel. This year Dr. Reynolds was able 
to measure the shortening, using lamb fe- 
tuses delivered by Caesarean section. With 
the cord pulsating, threads were tied onto 
the wall of an artery at a known distance 
apart. After constriction of the artery, the 
distance was measured again. The amount 
of shortening was thus ascertained to be 
between 14 and 16 per cent. Similar meas- 
urements on the ductus arteriosus showed 
a shortening of 20 to nearly 40 per cent. 
Thus shortening is an important compo- 
nent of vasoconstriction. 

Fetal vascular physiology. Twenty-five 
fetal lambs that were available during the 
winter were used by Dr. Reynolds prima- 
rily to study the mechanism of a physio- 
logical response of the fetal circulation, 
that is, a sudden decrease in heart rate, 
which is taken by obstetricians to indicate 
fetal distress, such as occurs, for example, 
when the umbilical cord is accidentally 
compressed. The current explanation is 
that an increase in fetal arterial pressure 
due to blockage of the umbilical arteries 
sets up reflex responses which oppose the 
rise; these would include slowing of the 
heartbeat. This hypothesis, for which there 
is some support in the literature, is based 
on a supposition that the fetus in utero is 
reacting like an adult in the outside world. 
This is not the case. 

Dr. Reynolds finds that the heart rate is 
slowed when the umbilical arteries alone 
are occluded (with a rise in blood pres- 



!Q CARNEGIE INSTITUTION OF WASHINGTON 

sure) and also when the umbilical veins necessary. Equipment for the work is now 

alone are occluded (with a fall in blood being installed. 

pressure). The immediate slowing is abol- Amniotic fluid. Several years ago, Dr. 
ished by cutting the nerve paths by which L. B. Flexner, then in this Department, 
the heart rate is controlled. This shows and his associates established that in two 
that nervous impulses arising from the species which they studied (guinea pig 
venous channels leading from the placenta and man) amniotic fluid is continuously 
to the heart are capable of regulating the formed and absorbed, with an increasing 
action of the heart. It appears that the turnover of water and presumably there- 
carotid sinus reflex path (via the 9th era- fore of the other constituents of the fluid, 
nial nerve nucleus), the sympathetic sys- No one knows what are the sites of for- 
tem (lateral reticulospinal tracts), and the mation, nor where the fluid leaves the am- 
vagus nerves (10th cranial nucleus) are not niotic space in which it is enclosed. Dr. 
functioning at a high level of activity, if at Reynolds has had an incidental opportu- 
all, when the fetus is at rest. When, how- nity, during his observations on fetal cir- 
ever, it is subjected to stress, these mecha- culation in lambs, to go into this question, 
nisms are called into play. Figuratively In experiments in which the head of the 
speaking, while the fetus is at rest the fetus was enclosed in a rubber bag, the 
wires are in place and the connections latter became full of secretions from the 
made, but the lines are not busy. With mouth cavity and nasopharynx. This oc- 
stress, they go into action. curred even though the esophagus and 

It was found that the resting fetal heart trachea were still open as possible avenues 
rate is governed, in a broad sense, by fetal of exit, by swallowing or absorption re- 
blood pressure. As the one increases, so spectively. As much as 30 cc was collected 
does the other, and vice versa. in 45 minutes. This observation points to 

When the fetal heart is completely freed at least one source of an appreciable por- 

of its sympathetic and parasympathetic tion of the amniotic fluid, and accounts for 

nerve connections, its beat becomes ex- the hitherto unexplained presence of a pro- 

tremely rapid when the fetus is subjected teid substance, mucin, in this fluid, 
to circulatory distress. The stimulus for 

this increase is blood-borne; it is removed Biochemistry of Spermatozoa and of the 
by adrenalectomy, and the active substance Genital Canals 
is probably, therefore, adrenaline. These With the facilities of the Department of 
considerations shed light on the puzzling Gynecology, Johns Hopkins Hospital and 
clinical picture that is seen when, as some- Medical School, the role of uterine mo- 
times happens in human labor, the fetal tility, including that of the cervix uteri, 
heart is slowed (bradycardia) by circula- in sperm transport in the human female is 
tory distress, and then later becomes exces- being investigated by Dr. D. W. Bishop, 
sively fast. The latter state is probably an It appears that in women who are artifi- 
indication that the infant is in extremis. daily inseminated just before complete 

A fuller understanding of these prob- hysterectomy, no penetration of sperma- 

lems requires study of the course and char- tozoa into the uterus occurs except dur- 

acteristics of blood flow from the placenta ing the ovulatory phase of the cycle. This 

through the fetal liver and into the heart; supports the findings of a number of 

for such a study X-ray cinematography is workers who have stated that in experi- 



DEPARTMENT OF EMBRYOLOGY 



I 9 I 



ments done in vitro, spermatozoa pene- 
trate the cervical mucus only when the 
latter is produced at mid-interval of the 
menstrual cycle, and that live spermatozoa 
can be aspirated from the uterus only if 
insemination takes place at about the time 
of ovulation. These observations are being 
continued as cases become available at the 
Hospital. 

Experiments are under way to deter- 
mine what role, if any, oxytocin plays in 
the process of sperm transport through the 
rabbit cervix. It has been suggested by re- 
cent American and British investigators 
that an oxytocic factor facilitates sperm 
migration through the cervix of the cow, 
and that oxytocin is released by copulation 
in the rabbit. Direct evidence of this 
mechanism is being sought. 

Dr. Bishop's studies, begun elsewhere, 
on the nature of the metabolic substrates 
utilized by the spermatozoa during their 
sojourn in the male genital ducts and dur- 
ing their passage through the female tract 
are being followed up by a chromato- 
graphic study of the hexose sugars con- 
tributed by the seminal vesicles and pros- 
tate gland. Of particular importance is 
the problem as to the degree of phos- 
phorylation of the monosaccharides when 
they are secreted. Two possibilities have 
been suggested. Either free fructose or 
glucose is secreted by the accessory glands; 
or fructo-phosphate or gluco-phosphate is 
secreted and subsequently dephosphoryl- 
ated in the semen. If the latter alternative 
is the correct one, significance is given to 
the presence of very large quantities of 
acid phosphatase supplied by the prostate 
gland and, incidentally, also by the female 
genital epithelium. 

Hydrogen-ion concentration in the ovi- 
ducts. A micro-method for determination 
of hydrogen-ion concentration inside hol- 
low organs, which Dr. Bishop previously 
used in an investigation of the rabbit's vas 



deferens, is being adapted to use in the 
oviduct. Whereas the hydrogen-ion con- 
centrations in the uterine cavity are fairly 
well known, those of the oviducts (Fal- 
lopian tubes) have not been determined. 
These pH studies bear on three important 
points: (1) the effect of pH changes on 
the "fertilizin-antifertilizin" type of reac- 
tion between gametes which Dr. Bishop 
studied last year at the California Institute 
of Technology; (2) the suggestion, made 
by investigators elsewhere, that a high 
tubal pH (8.5-9.0) may be responsible for 
the dispersion of the cumulus cells around 
the ovum; and (3) Dr. B. G. Boving's 
discovery of a localized region of high 
alkalinity in unimplanted rabbit blasto- 
cysts. 

Biochemistry and Physiology of 
Uterine Muscle 

The investigation of uterine muscle 
physiology is going ahead so rapidly and 
in such a sequential way that it is difficult, 
when reporting its status, to avoid a con- 
fusing overlap of results already published 
with the statement of work in progress. 
The reader is therefore advised to turn, at 
this point, to the corresponding section 
under "Published Research" in the latter 
part of the report, and only after reading 
that account to continue with the follow- 
ing summary of current phases of the 
program. 

During the past year Dr. Csapo obtained 
further evidence that intracellular potas- 
sium is involved in the contraction pat- 
tern of uterine muscle. This was given by 
the observation that small doses of proges- 
terone placed in the bath of physiological 
salt solution in which a strip of estrogen- 
dominated uterine muscle is contracting 
will result in a slight increase in tension, 
probably by lowering the intracellular po- 
tassium from the superoptimal to the op- 



192 



CARNEGIE INSTITUTION OF WASHINGTON 



timal concentration. If more progesterone 
is put in the bath, intracellular potassium 
will decrease below the optimal concen- 
tration and submaximal tension will be 
elicited. 

Potassium-sodium ratio in uterine mus- 
cle. However much the foregoing experi- 
ments appear to support the working hy- 
pothesis, they are not conclusive. Final 
proof can be obtained by showing that the 
intracellular potassium concentration, or 
the ratio K:Na, in the progesterone-dom- 
inated uterus is lower than that in the es- 
trogen-dominated uterus. To demonstrate 
this requires, as a preliminary, accurate 
determination of the extracellular space 
of the myometrium, about which nothing 
is known. Dr. Beni Horvath, who under- 
took this investigation, had to determine 
extracellular space as well as potassium- 
sodium concentration in rabbit uteri under 
the domination of each of the two ovarian 
hormones. His findings, which will be re- 
ported in full in a journal article, indicate 
(as was predicted from the physiological 
experiments with living muscle) that un- 
der progesterone domination the concen- 
tration of intracellular potassium and the 
K:Na ratio are lower than under estrogen. 

Uterine muscle contraction in situ. If 
our growing knowledge of the funda- 
mental nature of uterine muscle contrac- 
tion is to be useful in understanding the 
behavior of the uterus as an organ, and 
also those disturbances of uterine function 
with which the obstetrician is confronted, 
it will be necessary to find out whether the 
living, intact uterus responds to electrical 
stimulation in the same way as do isolated 
strips of muscle studied in vitro. Dr. 
Brenda M. Schofield joined the Depart- 
ment temporarily in order to carry out 
studies of this sort, for which she had be- 
gun at St. Andrews University (Dundee, 
Scotland) to work out a technical method. 
In Baltimore the technique has now been 



developed sufficiently to permit accurate 
measurement of the isometric tension de- 
veloped by the uterus in situ in the living 
animal. It has thus been found that the 
maximum work done by uterine muscle 
in vivo and in vitro is similar, and that be- 
havior in response to electrical stimulation 
is also similar. Dr. Schofield's most in- 
structive finding thus far is that the posi- 
tive and negative "staircases" of estrogen- 
and progesterone-dominated uteri occur in 
the living animal, closely resembling, when 
recorded graphically, the pattern previ- 
ously observed in vitro by Dr. Csapo and 
Dr. Corner. 

Significance of measuring isometric ten- 
sion. It has been the common practice, in 
studying the physiology of the myome- 
trium, to observe isotonic contraction by 
observing the movements of a light lever 
to which the muscle strip is attached. Dr. 
Reynolds emphasized long ago that con- 
clusions derived from such observations 
are frequently contradictory and do not 
give a coherent picture of the action of 
hormones and oxytocic drugs. Dr. Csapo 
finds that uterine muscle contracting iso- 
tonically is insensitive (within certain lim- 
its) to changes in temperature and in in- 
tensity of electrical stimulation. On the 
other hand, muscle contracting isomet- 
rically (i.e., pulling against an excessive 
load so that it does not, practically speak- 
ing, shorten in doing its work) responds in 
a strictly quantitative way to such changes 
in temperature and stimulus. His tentative 
explanation of these facts is that the uter- 
ine muscle is composed of a number of 
functional units. When under light load, 
or no load at all, maximum shortening can 
occur with only partial activation of these 
functional units. On the other hand, under 
optimum load the work done (or under 
isometric conditions, the tension devel- 
oped) quantitatively indicates the extent of 



DEPARTMENT OF EMBRYOLOGY 



193 



activation, that is to say, the relative num- 
ber of functioning units. 

From these considerations it is clear that 
the effect of drugs and hormones must be 
observed isometrically (or isotonically but 
with optimum load) if correct conclusions 
are to be drawn from the recorded con- 



tractions. Preliminary experiments with a 
well known oxytocic hormone, pitocin, not 
only illustrate this point, but give a new 
concept of the nature of pitocin action. A 
detailed account of these experiments and 
the new views to which they lead is in 
preparation for publication. 



CO-OPERATIVE RESEARCH ACTIVITIES 



Following upon previously reported co- 
operation by Dr. Elizabeth M. Ramsey in 
a study of prenatal mortality which is be- 
ing conducted at the Columbia University- 
Presbyterian Hospital Medical Center, 
New York City, under the direction of Dr. 
Katharine K. Merritt, Dr. Ramsey has ac- 
cepted appointment as a member of the 
advisory committee on a two-year continu- 
ation study of gestation, birth, and the first 
year of postnatal life by combined obstet- 
rical, pediatric, and pathological investiga- 
tion. Dr. Ramsey will continue to examine 
fetuses sent from New York City in con- 
nection with this investigation. 

Joint study of a possible cause of human 
infertility has been conducted by Dr. 
Bishop in collaboration with Dr. Georgi- 
ana Seegar-Jones, of the Department of 
Gynecology of Johns Hopkins University. 
The latter has isolated from several in- 
fertile women a vaginal fungus which is 
believed to have spermicidal properties. 
Attempts to establish this fungus in the 
vaginas of female monkeys have not yet 
been successful. 

On February 1, 1938 the Department of 
Embryology provided headquarters in its 
laboratory for a small group of scientific 
men led by Dr. Robert K. Enders, working 
on a study of reproduction in the mink 
under the auspices of the U. S. Depart- 



ment of Agriculture. The impetus for this 
project had come in part from Dr. Carl G. 
Hartman, then a member of the Depart- 
ment of Embryology. After a few months 
Dr. Enders was appointed to the faculty 
of Swarthmore College and his project was 
carried on there for three years, until it 
was transferred to the Fish and Wildlife 
Service, U. S. Department of the Interior. 
In 1946 the work was transferred to the 
Bureau of Animal Industry, U. S. Depart- 
ment of Agriculture. 

After fourteen years of intensive study 
Dr. Enders has published a report which 
constitutes a great advance in knowledge 
of the breeding and reproduction of this 
very important fur-bearing animal. In his 
report he expresses gratitude to Dr. George 
L. Streeter, Director of the Department 
of Embryology at the time when the 
Carnegie Institution fostered the project. 
Credit is also given to Osborne O. Heard, 
of the Department's staff, for technical 
photography, and to Arthur G. Rever for 
assistance in experimental surgical opera- 
tions. The Department of Embryology is 
pleased to see the evidence of a successful 
investigation in a field so close to its own 
interests, and to have had the opportunity 
of encouraging this excellent work in its 
earliest days. 



THE CARNEGIE COLLECTION OF EMBRYOS 

Through the efforts of Dr. G. W. Bar- University of Chicago has generously 
telmez, the Department of Anatomy of the added to its previous gifts another group of 



194 



CARNEGIE INSTITUTION OF WASHINGTON 



human embryos collected and prepared by 
Dr. Bartelmez when he was at Chicago. 
A special collection of serial sections of 
human embryonic limbs was received from 
the same source. 

The Department of Embryology has also 
acquired a collection of serial sections of 
rat embryos in late somite stages prepared 
by the late Professor F. L. Landacre, of 
Ohio State University. With the addition 
of these specimens to a set of ioo serially 
sectioned rat embryos in early somite states, 
in the possession of Dr. Bartelmez, the De- 
partment is well equipped for study of 
the development of the albino rat, an ani- 
mal which is much used in experimental 
embryology and for which, therefore, good 
morphological material is necessary for 
comparison and control. 

Dr. Elizabeth M. Ramsey and Miss Har- 
riet L. Caspari have made a most valuable 
contribution to the administration and 
housekeeping of the Collection by going 
through all the stored specimens which 
were shelved in bottles and jars, and cull- 
ing out all items which were found to have 
no research or museum value. 

Richard D. Grill, photographer, and 
Miss Caspari, with the advice of Dr. Bar- 



telmez, have completed an arduous, time- 
consuming review of the immense collec- 
tion of photographic negatives, numbering 
approximately 16,000 items. Useless and 
redundant negatives have been discarded; 
those of permanent value have been re- 
checked. This valuable archive is in con- 
stant use, not only to supply pictures 
needed for research and publication by the 
staff, but also to meet requests from embry- 
ologists elsewhere. It has always been kept 
in excellent order and is catalogued so that 
desired negatives are instantly available. 

Photographic records and models. Os- 
borne O. Heard prepared complete serial 
microphotographs of 12 presomite em- 
bryos. These serial pictures greatly facili- 
tate the process of modeling by the ad- 
vanced techniques in use at the laboratory, 
and are also useful for direct study, at least 
of details not requiring examination of the 
original sections, which are thus spared 
much handling and are less frequently ex- 
posed to the risk of breakage. Five older 
embryos were also photographed in com- 
plete serial sections. The remarkable early 
human twin embryo mentioned above (no. 
9009) was modeled by Mr. Heard. 



PUBLISHED RESEARCH 



Variability of the Menstrual Cycle 

The study of nature by scientists involves 
a constant effort to make an orderly ar- 
rangement of the facts observed, which 
often seem at first to be quite unrelated. In 
biology the facts usually cannot be taken 
out of their very complex setting and sub- 
jected to detached consideration, in any 
such way as that, for example, by which an 
astronomer can theoretically consider two 
heavenly bodies as geometrically regular 
and affecting each other independently of 
all other influences. Similar isolation of bio- 
logical phenomena generally has to neg- 



lect essential but imperfectly understood 
considerations without which the most ten- 
tative calculations are unsafe. Because, in 
spite of this, the effort to discover basic re- 
lationships in the life process must be 
made, biological thinking tends, even more 
than that of physical scientists, to alterna- 
tion in its approach. The first step in ana- 
lyzing a complex phenomenon is to work 
out a general explanatory theory or codifi- 
cation. This is accepted as a working basis 
and often gains currency in diagrammatic 
form. Then the pendulum swings. The 
exceptions and contradictions to the ac- 



DEPARTMENT OF EMBRYOLOGY 



195 



cepted "law" or principle begin to obtrude 
themselves and are critically pitted against 
the generalized theory. The diagram that 
seemed to be adequate or at least useful 
must often be discarded or redrawn. 

A process of this inevitable sort has oc- 
curred in the analysis of the female repro- 
ductive cycle. By the efforts of numerous 
biologists and physicians, beginning about 
1890, the once mysterious recurrent phe- 
nomenon of menstruation in the human 
female, and the obviously related but 
strangely diverse periodic sexual phenom- 
ena in other mammals, have been ana- 
lyzed. The way in which these cycles are 
controlled by interaction of the ovarian 
hormones with those of the pituitary gland 
is understood in principle, even if not yet 
completely in detail. The once baffling ex- 
ternal differences between the human men- 
strual cycle and the estrous cycles of the 
familiar domestic animals have been ex- 
plained, and a unified general concept of 
the mammalian cycle has been established. 

In all this work the natural tendency of 
investigators has been toward a simplified 
concept of the cycle. As a result, an over- 
rigid picture has tended to develop, par- 
ticularly with respect to the primate men- 
strual cycle. For purposes of comparison 
of one cycle with another, a convenient pat- 
tern of the cycle has been constructed upon 
the modal menstrual interval of 28 days. 
Changes occurring in the uterus and else- 
where have been conformed to the 28-day 
schedule in an over-precise way, and the 
variability of the intrinsic phases of the 
cycle, for instance the preovulatory and 
postovulatory periods, has been too much 
neglected. The quantitative precision of 
embryological data (such as the age of 
very early human embryos), of physiologi- 
cal hypotheses about cyclic events, and of 
clinical diagnoses concerning abnormalities 
of the cycle is in danger of overemphasis. 

Dr. G. W. Bartelmez has presented, in 



his study of factors in the variability of the 
menstrual cycle, a cogent exposition of this 
variability and of the limits which it im- 
poses upon the precision with which inter- 
nal events of the cycle can be timed from 
clinical information, that is, the menstrual 
history. His essay is the result of three dec- 
ades of personal research on the cycle in 
women and the rhesus monkey, as well as 
of extensive acquaintance with the litera- 
ture. This is not, fortunately, one of those 
situations in which critical reconsideration 
of the data threatens to render the whole 
current theory obsolete; but it certainly 
warns against overdiagraming of the work- 
ing concepts. Dr. Bartelmez' summary of 
his article follows. 

Abrupt fluctuations in successive men- 
strual cycles may occur even in "regular" 
individuals, and errors are likely to result 
from the application of statistical modes 
and means to particular cycles. Mathemati- 
cally all cycles in a statistical group are 
treated as identical, yet two cycles with sim- 
ilar external features such as length may 
differ fundamentally even to the extent of 
one's being ovulatory, the other anovula- 
tory. Tests and other signs of ovulation 
may be positive when the dominant follicle 
fails to rupture and is resorbed or becomes 
cystic, and the particular cycle is ano- 
vulatory. 

The fluctuations in the time relations 
during the cycle appear to be due to varia- 
tions in the ebb and flow of the controlling 
hormonal tides. A long cycle may be due 
to a long postmenstrual (quiescent) phase, 
to a long-lived corpus luteum, or to a long 
premenstrual (ischemic) phase. 

The time of ovulation even in the rhesus 
monkey has rarely been determined with 
an accuracy of less than 12 hours, and the 
time that may elapse between insemination 
and fertilization is unknown in primates. 
It is known that even normal siblings may 
develop at different rates, so that one can- 



196 



CARNEGIE INSTITUTION OF WASHINGTON 



not extrapolate with confidence from the 
most accurately timed cases to others less 
satisfactorily dated. Consequently we are 
rarely in a position to state the age of a 
pregnancy in any primate with greater ac- 
curacy than ±2 days. 

The morphological changes in the ova- 
ries provide the only satisfactory criteria 
for determining the sequence of events 
during the cycle. The target organs are less 
satisfactory, for they are subject to other 
factors than hormonal tides. This is true 
also of systematic changes such as fluctua- 
tions in basal temperature. In abundant 
material from rhesus monkeys, the endo- 
metria have been classified on the basis of 
ovarian findings, and obvious differences 
have been found in endometria associated 
with similar ovarian conditions. Even 
when these endometria are arranged in as 
many as eight groups corresponding to the 
phases of the ovarian cycle, there are speci- 
mens which exhibit some features of one 
group and others of the succeeding group. 

Umbilical Cord and Ductus Venosus 

Sphincter of the ductus venosus. The 
ductus venosus of the fetus is a direct chan- 
nel from the umbilical vein to the inferior 
vena cava, by which blood returning from 
the placenta is enabled to by-pass the fetal 
liver. In its wall there is a muscular 
sphincter, only recently discovered, which 
controls the rate of flow through the duc- 
tus and thus aids in maintaining physio- 
logical pressure in the umbilical vein. This 
control must of course be necessary to the 
fetus; and it also probably protects the um- 
bilical cord against dangerous kinks by 
keeping the cord vessels turgid. A knowl- 
edge of the development of the sphincter 
of the ductus venosus is obviously impor- 
tant in understanding the pattern of um- 
bilical blood flow in the growing embryo 
and fetus. Dr. Anna W. Chacko and Dr. 



Reynolds have published a study of this 
question. 

When the human embryo is 6.5 mm 
long (crown-rump length), the ductus ve- 
nosus is already well formed. At this time 
the incipient sphincter first becomes visible 
as a thickening of the endothelium at the 
junction of the umbilical recess and ductus 
venosus. As the embryo grows, the sphinc- 
ter is more elaborately organized, and by 
the 49th day of intrauterine life it has as- 
sumed its definitive form and structure. It 
contains circular and longitudinal fibers of 
smooth muscle, intermingled with elastic 
tissue. It is innervated by nerve fibers of 
vagal origin, coming from the region of 
the inferior vena cava and umbilical recess. 

Connective tissue (Wharton's jelly) of 
the umbilical cord. Pictured cross sections 
of the umbilical cord, such as are presented 
in textbooks, usually show the cord vessels 
emptied of their blood. The cord thus 
appears to be composed largely of loose 
connective tissue of the embryonic type 
(Wharton's jelly), in which run relatively 
narrow arteries and veins, occupying only 
a small part of the cross-sectional area. Dr. 
Reynolds, in his article on this subject, pre- 
sents photographs of cords of the human 
species, sheep, and goat, which show the 
comparison between cords in which the 
blood vessels are full of blood as in life, and 
others collapsed as they are when drained 
of blood. In the functional condition the 
expanded vessels occupy most of the cross- 
sectional areas, crowding the Wharton's 
jelly between the vessels and against the 
capsular tissue of the cord, until the con- 
nective tissue is hardly more than an ad- 
ventitial sheath tautly drawn around the 
arteries and veins. When the vessels con- 
strict on being emptied, they shorten and 
thicken, and the Wharton's jelly shortens 
and thickens also. The occurrence of short- 
ening of the vessels as an element in con- 



DEPARTMENT OF EMBRYOLOGY 



197 



striction is being studied (see above under 
"Research in Progress") and will be dis- 
cussed in a forthcoming publication. 

In the course of this study, Dr. Reynolds 
was able to elucidate the nature of the 
"folds of Hoboken" described in 1669 by 
the Dutch anatomist of that name. These 
are not valves as Hoboken thought, but 
crescentic transverse bands of the lining 
(intima) of the vessels. They presumably 
exist in life, for they can be seen in umbili- 
cal arteries which have been fixed in the 
distended state without ever having been 
allowed to collapse. Their function, if any, 
remains obscure. 

Blood flow in the umbilical arteries. In 
Year Book No. 51 (1951-1952), a paper on 
this subject by Dr. Reynolds and those 
with whom he worked at the Nuffield 
Institute, Oxford, in 1951-1952 was ab- 
stracted. This included the statement, sur- 
prising at first sight, that the umbilical ar- 
teries do not dilate and contract with the 
pulse wave. Their diameter remains con- 
stant, within the limits of very close meas- 
urement, throughout the cycle of pulsation. 
Dr. Reynolds, with Dr. F. W. Light, of 
Johns Hopkins University, Baltimore, and 
Dr. Ardran and Dr. Prichard, of Oxford, 
has now presented a full statement on the 
qualitative nature of pulsatile flow in the 
umbilical blood vessels. A summary of the 
conclusions follows. 

Insertion into an umbilical artery of a 
needle for recording blood pressure un- 
avoidably distorts the wall of the vessel 
and the streamlines of flow. For this rea- 
son true pressures like those in the intact 
artery cannot be recorded by this method. 
True lateral pressures were measured from 
the first branch of an umbilical artery. The 
vessel was fixed at right angles to the axis 
of the main vessel, and the pressure trans- 
mitted by means of a capacitance manome- 
ter for recording. 

When a long segment of umbilical cord 



was directly photographed by X-ray mov- 
ing pictures, using Thorotrast to make the 
vessel visible, and recording pressures as 
described above, it was found that at no 
time in the pulse pressure wave was there 
a demonstrable change in diameter of the 
artery. Similarly, there was no difference 
in the diameter of the artery along its 
course such as would be expected if, owing 
to frictional loss of energy, there were a 
significant decrease of pressure within the 
artery. 

Pressure pulses were recorded in the um- 
bilical artery and umbilical vein simultane- 
ously. They were 180° out of phase with 
each other, since the pulse pressure in the 
vein decreased as that in the artery in- 
creased, and vice versa. 

Study of streamlines of blood flow by 
X-ray cineangiography show that when a 
quick velocity component of the moving 
fluid during an arterial pulse wave hits 
part of the umbilical artery, the vessel 
may be displaced slightly. Such movement 
gives rise to visible arterial pulsation. 
There is no increase in arterial diameter 
(except in the arch of the aorta) measur- 
able by the methods used in this study, 
that is, in direct cineangiograms recorded 
at a frequency of twenty frames per second. 

Normal umbilical vein pressure is high 
if the flow is unobstructed, being equiva- 
lent to 30-40 mm of mercury. 

The rate of blood flow in the umbilical 
vessels is very variable, being inversely re- 
lated to the diameter of the vessels. The 
volume of flow in the two arteries per kilo- 
gram of body weight per minute is be- 
tween 300 and 400 cc. This is about two- 
thirds the volume that goes through the 
descending aorta. 

Fetal Circulation 

In the fetus, blood flows from the pulmo- 
nary artery to the aorta through the ductus 
arteriosus. It is therefore reasonable to as- 



198 



CARNEGIE INSTITUTION OF WASHINGTON 



sume that the pressure in the pulmonary 
trunk is greater than that in the aorta. In 
the adult animal, on the other hand, the 
pulmonary arterial pressure is very much 
less than the aortic pressure. Presumably 
the change takes place at or near the time 
of birth; but available technical methods 
have been inadequate for exact timing of 
this event and for the solution of many re- 
lated problems of fetal blood circulation. 
In a paper by Ardran, Dawes, Prichard, 
and Wyatt of Oxford, and Reynolds of the 
Department of Embryology, an account is 
given of an investigation carried out at the 
Nuffield Institute of Medical Research, at 
the instigation of Dr. Reynolds. 

By taking X-ray motion pictures at a 
speed of 25 frames per second, cinemato- 
grams of the fetal and neonatal circulation 
were obtained which correctly represented 
the cardiac cycle. It was found, contrary 
to expectation, that before respiration be- 
gins there is virtually no circulation of 
blood through the lung of the fetal lamb. 
Almost two-thirds of the blood put out by 
the heart goes to the placenta. The earlier 
study by Reynolds, Light, and co-workers, 
cited above, shows that the factor which 
controls the amount of blood going to the 
placenta is the cardiac output, not the size 
or length of the umbilical cord, nor any 
limiting factor in the placenta itself. In 
this mechanism it is essential that the di- 
ameter of the umbilical arteries and veins 
be ample, so that the energy lost by blood 
flowing in the cord shall be very small in 
comparison with the total energy of the 
moving blood. 

For the first time, in the work reported 
here blood pressure was measured in the 
fetal pulmonary trunk and aorta, and at 
each end of the ductus arteriosus. In the 
fetus, blood flows through the ductus un- 
der considerable pressure. When the infant 
begins to breathe, the blood is immediately 
diverted from the ductus arteriosus into the 



pulmonary arteries; and as the lungs ex- 
pand, the volume rate of flow through 
them increases almost fivefold. The pres- 
sure in the pulmonary trunk drops to a 
low point. Since the flow through the 
lungs has increased concomitantly with a 
fall in pressure, it must be inferred that 
the resistance to flow has in some way been 
reduced by the distention of the air spaces. 
During the first few minutes after this ini- 
tial change, the systemic blood pressure 
also falls, apparently because of the trans- 
fer to the lung of a significant portion of 
the total blood of the infant. This transi- 
tory general fall of blood pressure at the 
onset of respiratory movements, which has 
not previously been observed, may (if 
overlarge) be dangerous. Several obstetri- 
cians who have attended medical meetings 
at which Dr. Reynolds discussed these find- 
ings have already made use of them with 
good effect in the management of circula- 
tory conditions in the newborn infant. 

Effective closure of the ductus arteriosus 
was found to follow immediately upon the 
first aeration of the lungs, and thus to be 
associated with the changes of pressure and 
flow described above. It appears that as 
the blood is diverted into the lungs because 
of the lowered resistance to flow in these 
organs, this diversion of flow and the ac- 
companying fall in blood pressure in the 
ductus permit constriction and shortening 
of the ductus by action of the elastic fibers 
and smooth muscle cells in its wall, and 
thus lead to the obliteration of its lumen. 

Volume of Blood in Placenta 

Dr. Fritz Fuchs, of Copenhagen, who 
spent a year in the Department recently 
working with Dr. Louis B. Flexner, has 
reported a study of the volume of the red 
blood cells in the vessels of the placenta 
(guinea pig) . The estimates were made by 
using red blood corpuscles labeled with 



DEPARTMENT OF EMBRYOLOGY 



199 



a radioactive phosphorus isotope. It was 
found that late in pregnancy (57 days to 
term) the placentas in a given animal con- 
tain about 10 per cent of the body blood 
volume. The content of the fetal blood ves- 
sels of the placenta is equal to the amount 
of blood on the maternal side. The red cell 
volume is higher on the fetal side. The 
placentas contain 11 to 18 per cent of the 
total fetal blood, and 55 to 79 per cent of 
the fetal blood passes through the placenta 
in one minute. 

Oxytocic Drugs 

Dr. Reynolds, with his long experience 
in the physiology of the uterus as a con- 
tractile organ, continues to be called upon 
by clinical associates to assist in the plan- 
ning and analysis of their experimental 
studies. Physicians at the New York State 
College of Medicine (Cumberland Hospi- 
tal), Brooklyn, namely Drs. Altman, Lu- 
bin, Waltman, and Tisdall, joined with 
him during the past year in the publica- 
tion of two brief papers on drugs used in 
obstetrical practice. One of these deals 
with the safe use of pituitrin in difficult 
labor, by intravenous injection. The other 
discusses the action on the uterus of a 
newly introduced spasmolytic drug, dehy- 
droergotamine-45, which is an antagonist 
of adrenaline. In this latter work the toko- 
dynamometer developed by Dr. Reynolds 
with the assistance of Mr. Heard, men- 
tioned in several previous Year Books, was 
used as the chief research instrument. The 
results, which are chiefly of clinical impor- 
tance, need not be discussed here. 

Biochemistry and Physiology of 
Uterine Muscle 

Results thus far achieved in the intensive 
long-term investigation of the biochemis- 
try and physiology of uterine muscle, led 
by Dr. Csapo, were summarized in the 



Ciba Foundation Lecture delivered by Dr. 
Corner on behalf of Dr. Csapo and himself 
at London in December 1952 and pub- 
lished in March 1953 (see bibliography). 
Some of the findings described in this lec- 
ture, and in two papers by Csapo and Cor- 
ner, have received preliminary mention in 
previous Year Books, especially No. 51 
(1951-1952), pages 166-167. E* r - Csapo 
proved several years ago that the well 
known contractile protein complex of vol- 
untary muscular tissue, known as actomyo- 
sin, exists also in the involuntary uterine 
muscle. He has now proved that this sub- 
stance is the specific contractile material 
in uterine muscle. Having discovered that 
the concentration of actomyosin is con- 
trolled by the ovarian estrogenic hor- 
mone, Dr. Csapo obviously had available a 
method for altering the amount present at 
a given time: that is to say, by administra- 
tion of graded doses of estrogen to cas- 
trated female rabbits, thus building up 
the uterine tissue to any required degree. 
When this was done, it was found that the 
work which the muscle can do under stim- 
ulation is strictly proportional to the con- 
centration of actomyosin in the tissue. 

Dr. Csapo, Dr. J. Gergely, and Dr. J. H. 
Menkes have shown that not only the con- 
tractile protein (actomyosin), but also the 
energy-rich substance which provides fuel 
for the contractions (adenosine triphos- 
phate, "ATP") is controlled by the estro- 
genic hormone. The amounts of the two 
substances run parallel, probably by reason 
of a quantitative molecular (stoichometric) 
relation between them. The rate of forma- 
tion of one of them is evidently regulated 
by the other; presumably the myosin com- 
ponent of actomyosin, acting as an enzyme 
(ATP-ase), is involved in this relation. 

The accuracy of the above-stated conclu- 
sion that actomyosin is the specific contrac- 
tile agent, and the quantitative value of 



200 CARNEGIE INSTITUTION OF WASHINGTON 

what follows in this summary, depend on behavior of uterine muscle in vitro. Pre- 
the use of isometric rather than isotonic liminary experiments indicated that under 
measurement of uterine muscle activity. A estrogen domination the resting uterus con- 
fuller theoretical explanation of this point, tains more intracellular potassium than is 
and a discussion of its implications, which necessary for the development of maxi- 
are now being explored, will be found ear- mum tension, and therefore the muscle has 
lier in this report, under "Research in to be stimulated frequently to make it lose 
Progress." intracellular potassium and thus develop 

Early in the course of preliminary ex- maximum tension. On the contrary, the 
periments on the recording of isometric uterus under progesterone domination con- 
muscle, Dr. Csapo and Dr. Corner discov- tains less potassium than is optimal for 
ered that uterine muscle, like that of the maximum tension, and consequently the 
heart, exhibits the "staircase phenome- more frequently it is stimulated, the less 
non"; that is, the tension it exerts at a tension is developed. 

single contraction depends on the length Dr. Csapo then measured the maximum 

of time since the previous contraction. tension developed by strips of estrogen- 

Within certain limits, the longer the inter- dominated uteri as the K:Na ratio in the 

val, the less the tension developed. Using bath was increased in regular steps. It is 

castrate rabbits injected with the two ovar- known from the work of others that such 

ian hormones, it was then found that the treatment results in a moderately increased 

characteristic slope of the staircase of uter- K:Na ratio inside the cells. Csapo found 

ine muscle under the influence of estrogen that as the ratio is increased, the tension 

is reversed under progesterone domination, gradually decreases, a result which agrees 

It is evident therefore that the two hor- with the hypothesis that the estrogen-domi- 

mones have opposing effects on some fac- nated muscle originally contained more 

tor or factors intimately involved in the than the optimal intracellular concentra- 

mechanism of contraction. tion of potassium. It was found that pro- 

By a fortunate coincidence, at the very gesterone-dominated uteri, on the contrary, 
time when the existence of a staircase ef- under similar treatment develop increased 
feet in uterine muscle and its dependence tension, at least up to a certain point. This 
on the ovarian hormone were thus discov- supports the belief that the uterus under 
ered, Professor A. Szent-Gyorgyi and Dr. the action of this hormone has a subopti- 
S. Hajdu were at work, at the Marine Bio- mal potassium concentration inside the 
logical Laboratory, Woods Hole, on the cell. Decrease of the temperature at which 
nature of the staircase phenomenon in frog the muscle is working gradually abolishes 
heart muscle. They had formed a hypoth- the positive staircase and increases the slope 
esis that the staircase is related to a system- of the reversed staircase, whereas increase 
atic change in the concentration of potas- of temperature has the opposite effects, 
sium in the muscle cells during the phase This hypothesis, which assumes that the 
of resumed activity. For further test of this contractile power of uterine muscle in vitro 
idea, uterine muscle is especially favorable is related to the potassium content of the 
because of its slow contractions, its gen- muscle cells, obviously calls for further 
eral controllability, and particularly the study in many directions. The continua- 
reversibility of its staircase. Dr. Csapo tion studies now under way in the Depart- 
therefore proceeded to study the effects of ment of Embryology are outlined above 
varying concentrations of potassium on the under "Research in Progress." 



DEPARTMENT OF EMBRYOLOGY 



201 



Technical Methods 

Dr. Bent G. Boving has designed and 
constructed an ingenious apparatus for ob- 
serving the interior of the pregnant rabbit 
uterus and the living embryos in the blas- 
tocyst and implantation stages. This con- 
sists of a transparent plastic chamber 
within which a segment of the uterine 
horn may be held practically immobile un- 
der the microscope. Provision is made for 
illumination and for experimental access 
to the specimen under observation. With 
the aid of this apparatus he has observed 



and photographed the blastocyst stage of 
embryonic development in situ and has 
watched and experimented on the earlier 
stages of the process of attachment of the 
embryo to the uterine lining. 

Mr. O. O. Heard has renewed his inter- 
est in the role of surface forces in the cut- 
ting of microscopic sections. By treatment 
of the cutting facet of the knife with sub- 
stances having a low coefficient of friction, 
contamination of the facet with paraffin is 
practically eliminated and distortion of the 
section by compression is reduced. A re- 
port has been prepared for press. 



DIFFUSION AND APPLICATION OF RESEARCH RESULTS 



Consultative services. Dr. S. R. M. Reyn- 
olds devoted considerable time during the 
year (two weeks in September and one or 
two days monthly from October to March) 
to participation in the work of a group as- 
sembled by the Conservation Foundation 
of New York City for the study of prob- 
lems of overpopulation and the limitation 
of reproductive rates. Dr. Corner, before 
leaving for England, also took part in a 
conference of this group. 

The Department of Parasitology of the 
Johns Hopkins University, School of Hy- 
giene, is conducting an important research 
program in vertebrate ecology with special 
reference to the problems of rat infestation 
in cities. To assist in the orientation of 
those taking part in this investigation, four 
members of the Department of Embry- 
ology (Bishop, Boving, Burns, Reynolds) 
led a series of seminars on the physiology 
of reproduction, from October 1952 to May 

*953- 

Reviews. Members of the Department 
were called upon, even more extensively 
than in past years, to prepare reviews of 
progress in their respective fields of re- 
search. Some of these reviews were pre- 
sented only in print, others were first de- 



livered as lectures. The Ciba Foundation 
Lecture of Dr. Corner and Dr. Csapo com- 
prised not only the already cited report of 
current research by the authors, but also a 
historical review of research during the 
past half century on the action of ovarian 
hormones on uterine muscle. 

Dr. R. K. Burns began the preparation 
of a chapter on the role of sex-gland hor- 
mones in the differentiation of the em- 
bryonic reproductive system, for the new 
(third) edition of the important handbook 
Sex and Internal Secretions. 

Dr. S. R. M. Reynolds published during 
the year a volume, Physiological Bases of 
Gynecology and Obstetrics, based on his 
lectures at Montevideo, Uruguay, in 1950. 
The book, which is intended for physi- 
cians, presents an account of his varied re- 
searches, much of which has been cited in 
these annual reports during the past years. 
The Scientific American for July 1952 con- 
tained an illustrated semipopular review 
by Dr. Reynolds of his recent work on the 
umbilical cord. 

Dr. David W. Bishop contributed a 
chapter on the metabolism of the sperma- 
tozoa to a published symposium on the 
testis and ovary, eggs and sperm cells. He 



202 



CARNEGIE INSTITUTION OF WASHINGTON 



has in press a chapter on the biology of 
spermatozoa in the new edition of Sex and 
Internal Secretions. 

Dr. Louis B. Flexner, Research Associ- 
ate, has also written a chapter for Sex and 
Internal Secretions, on the physiology and 
biochemistry of the placenta. A recent vol- 
ume on the biology of mental health and 
disease contains a chapter by Dr. Flexner 
reviewing his studies on the physiological 
development of the brain cortex. His Har- 
vey Society lecture, cited in the bibliog- 
raphy below, is also a review of aspects of 
this subject. 

Lectures. During his incumbency of the 
George Eastman Visiting Professorship at 
Oxford, Dr. Corner gave lecture courses, 
during two terms, on embryology, the 
physiology of reproduction, and the his- 
tory of medicine. He delivered lectures 
also at London (two), Cambridge, Edin- 
burgh (two), Belfast (two), Copenhagen 
(two), Lund, and Oslo. 

Dr. Burns gave six lectures at the Johns 
Hopkins Medical School, including two 
talks for the Anatomy Department, three 
in Urology, and one in the Women's 
Clinic. He also spoke at the Armed Forces 
Institute of Pathology, Washington, D. C. 

Dr. Reynolds gave three lectures at the 
Johns Hopkins Medical School, including 
one in Pediatrics and two in Medicine. He 
presented lectures and talks at the Cardio- 
vascular Laboratory, U. S. Public Health 
Service (Washington), the Obstetrical So- 
ciety of Boston, the Brooklyn Gynecologi- 
cal Society, the American College of Sur- 
geons (in a panel discussion), the Research 
Laboratories of Merck and Company, and 
hospital staffs in several cities. He de- 
livered formally designated lectures at 
Wayne University and the University of 
Michigan. 

Dr. Csapo lectured once each for three 
departments of the Johns Hopkins Medi- 



cal School, namely, Medicine, Ophthalmol- 
ogy, and the Women's Clinic. He took 
part in a symposium on the biological role 
of potassium, held at the University of 
Minnesota in September 1952. His con- 
tribution will be published. 

Dr. Bishop gave six seminar talks at 
Swarthmore College and also lectured at 
the Johns Hopkins Medical School (Wom- 
en's Clinic), the Johns Hopkins School of 
Hygiene, and Goucher College. 

Dr. Ramsey gave a course of lectures in 
obstetrical and gynecological pathology at 
George Washington University, School of 
Medicine. 

The Research Associates of the Depart- 
ment were also in demand for lectures on 
the work done at the laboratory or in asso- 
ciation with it. Dr. C. H. Heuser ad- 
dressed the Georgia Medical Society on 
young human embryos, and the County 
Medical Society of Spartansburg, South 
Carolina, on placentation in the opossum. 
Dr. Arthur T. Hertig spoke before the 
New England Pathological Society and the 
Pittsburgh Obstetrical and Gynecological 
Society, on the pathology of very early hu- 
man embryos. Dr. Louis B. Flexner's Har- 
vey Society lecture has been cited above 
under "Reviews." He was also Ferris Me- 
morial Lecturer at Yale University, speak- 
ing on the development of the cerebral 
cortex. 

Mr. Chester F. Reather, former depart- 
mental photographer, is the author of 
an article, "Photography in Embryology," 
published in the Eastman Kodak Com- 
pany's periodical, Medical Radiography 
and Photography. A beautifully printed 
two-page chart of human and primate em- 
bryonic development which accompanied 
the article was reproduced for use on a 
wall chart and has been widely distributed 
to teachers of embryology by the Eastman 



DEPARTMENT OF EMBRYOLOGY 



203 



Kodak Company. All the illustrations Grill, Mrs. Padget, and Miss McCarthy all 

were made by Mr. Reather from specimens gave help in this matter. 

in the Carnegie Collection. Scientific illustrations. At the Annual 

Visiting groups. In October 1952, the Meeting of the Carnegie Institution of 
Department of Embryology was honored Washington in December 1952, Mr. James 
by a visit of the Canadian Gynecological F. Didusch, departmental artist since the 
Visiting Club, at which a series of talks foundation of the laboratory, arranged an 
and demonstrations was arranged by mem- exhibit of more than 150 drawings repre- 
bers of the Department. In the spring of senting his life work as illustrator of em- 
1953 a demonstration was arranged for the bryological, surgical, and gynecological re- 
Junior Honors Seminar, Department of search. The exhibit included examples of 
Zoology, Swarthmore College; and the the technical procedures of illustration at 
senior biology class of the Bryn Mawr Pre- all steps from the original specimen to the 
paratory School, Baltimore, was given a published plate. Mary E. McCarthy, as- 
tour of the laboratory and a demonstration sistant modeler, also showed a panel of il- 
of human embryology. lustrations. Mr. Didusch's pictures were 

Motion picture film. Progress is being again shown in January and February 1953 

made on a film illustrating the develop- at the Department of Embryology. The 

ment of the human ear and auditory or- great appreciation which the exhibit re- 

gans, to be produced under the auspices of ceived is a tribute to his unequaled skill as 

the American Academy of Ophthalmology an anatomical artist and his constant striv- 

and Otolaryngology, by the scientific mo- ing for accuracy and perfection of style, 

tion picture firm of Sturgis and Grant. In Mr. R. D. Grill entered four photo- 

this undertaking, which follows the highly graphs made by him in the course of the 

successful film on the embryology of the Department's research program, in the 

eye mentioned in previous Year Books, the 17th Rochester International Salon of Pho- 

Department is again contributing techni- tography and the 10th Syracuse Salon. All 

cal advice and the use of illustrative ma- four entries were hung in the two exhibi- 

terial. Dr. Bartelmez, Mr. Heard, Mr. tions. 



BIBLIOGRAPHY 



Aberle, S. D. See Corner, G. W. 

Altman, S. G., R. Waltman, S. Lubin, and 
S. R. M. Reynolds. Oxytocic and toxic 
actions of dihydroergotamine-45. Amer. 
Jour. Obstet. and Gynecol., vol. 64, pp. 101- 
109 (1952). 

Ardran, G. M., G. S. Dawes, M. M. L. Prichard, 
S. R. M. Reynolds, and D. G. Wyatt. The 
effect of ventilation of the foetal lungs upon 
the pulmonary circulation. Jour. Physiol., 
vol. 118, pp. 12-22 (1952). 

See Reynolds, S. R. M. 

Bartelmez, G. W. Factors in the variability of 
the menstrual cycle. Anat. Rec, vol. 115, 
pp. 101-120 (1953). 

BooJ^ review: Purkyniana, by Jan Ev. 



Purkyne. Anat. Rec, vol. 116, pp. 117-119 

(i953)- 
Bishop, D. W. The metabolic machinery of 

sperm activity. In: Studies on testis and 
ovary, eggs and sperm, ed. E. T. Engle, pp. 
95-110. Springfield, 111., C. C. Thomas 
(1952). 

and A. Tyler. Reactions of mammalian 

spermatozoa to egg substances. (Abstract) 
Anat. Rec, vol. 113, p. 526 (1952). 

Boving, B. G. Internal observation of rabbit 
uterus. Science, vol. 116, pp. 211-214 (1952). 

Boo\ review: Medicinens Historie, by 

E. Gotfredsen. Bull. Hist. Med., vol. 27, pp. 
79-82 (1953). 

Chacko, A. W., and S. R. M. Reynolds. Em- 
bryonic development in the human of the 



204 



CARNEGIE INSTITUTION OF WASHINGTON 



sphincter of the ductus venosus. Anat. Rec, 
vol. 115, pp. 151-173 (i953)- 
Corner, G. W. The events of the primate 
ovarian cycle. (21st Huxley Lecture, Char- 
ing Cross Hospital, London, May 28, 1952.) 
Brit. Med. Jour., vol. 2, pp. 403-409 (1952). 

Attaining manhood: A doctor talks to 

boys about sex and reproduction. English 
edition, revised. London, Allen and Unwin 

(i953)- 

Attaining womanhood: A doctor talks 

to girls about sex and reproduction. English 
edition, revised. London, Allen and Unwin 

(i953)- 

and S. D. Aberle. Twenty-five years of 

sex research: History of the National Re- 
search Council Committee for Research in 
Problems of Sex, 1922-1947. 248 pp. Phila- 
delphia, W. B. Saunders Co. (1953). 

and A. I. Csapo. Action of the ovarian 

hormones on uterine muscle. (4th Ciba 
Foundation Lecture, London, December 4, 
1952.) Brit. Med. Jour., vol. 1, pp. 687-693 

0953) • 

See Csapo, A. I. 



Csapo, A. I., and G. W. Corner. The antagonis- 
tic effects of estrogen and progesterone on 
the staircase phenomenon in uterine muscle. 
Endocrinology, vol. 51, pp. 378-385 (1952). 

The effect of estrogen on the 

isometric tension of rabbit uterine strips. 
Science, vol. 117, pp. 162-164 (1953). 

See Corner, G. W. 



Dawes, G. S. See Ardran, G. M. 

Enders, R. E. Reproduction in the mink (Mus- 
tela visoti). Proc. Amer. Philos. Soc, vol. 
96, pp. 691-755 (1952). 

Flexner, L. B. The development of the cerebral 
cortex: A cytological, functional, and bio- 
chemical approach. The Harvey Lectures, 
ser. 47, pp. 156-179. New York, Academic 
Press (1951-1952). 

Physiologic development of the cortex of 

the brain and its relationship to its morphol- 
ogy, chemical constitution, and enzyme 



systems. In: The biology of mental health 
and disease, chap. 13. New York, Paul B. 
Hoeber (1952). 
Fuchs, F. The red cell volume of the maternal 
and foetal vessels of the guinea pig placenta. 
Acta physiol. scandinav., vol. 28, pp. 162-171 

(i953). 
Gilbert, P. W. The premandibular head cavities 
of the opossum, Didelphis virginiana. (Ab- 
stract) Anat. Rec, vol. 115, pp. 392-393 

(i953)- 
Light, F. W., Jr. See Reynolds, S. R. M. 
Lubin, S., R. Waltman, L. Tisdall, and S. R. M. 

Reynolds. An evaluation of intravenous 

pituitrin. Amer. Jour. Obstet. and Gynecol., 

vol. 64, pp. 248-259 (1952). 

See Altman, S. G. 

Prichard, M. M. L. See Ardran, G. M.; Reyn- 
olds, S. R. M. 

Reather, C. F. Photography in embryology. 
Med. Radiogr. and Photogr. (Eastman 
Kodak Co.), vol. 28, pp. 12-19 ( T 95 2 )- 

Reynolds, S. R. M. Physiological bases of gyne- 
cology and obstetrics. Springfield, 111., C. C. 
Thomas (1952). 

The proportion of Wharton's jelly in the 

umbilical cord in relation to distention of 
the umbilical arteries and vein, with obser- 
vations on the folds of Hoboken. Anat. Rec, 
vol. 113, pp. 365-377 (i95 2 )- 

The umbilical cord. Sci. American, vol. 

187, pp. 70-74 (1952). 

F. W. Light, Jr., G. M. Ardran, and 

M. M. L. Prichard. The qualitative nature 
of pulsatile flow in umbilical blood vessels, 
with observations on flow in the aorta. Bull. 
Johns Hopkins Hosp., vol. 91, pp. 83-104 
(1952). 

See Altman, S. G.; Ardran, G. M.; 



Chacko, A. W.; Lubin, S. 
Tisdall, L. See Lubin, S. 
Tyler, A. See Bishop, D. W. 
Waltman, R. See Altman, S. G.; Lubin, S. 
Wyatt, D. G. See Ardran, G. M. 



DEPARTMENT OF GENETICS 

Cold Spring Harbor, Long Island, New Yor\ 
M. DEMEREC, Director 



The most important event of the past 
year was the completion of our construc- 
tion program, which provided two new 
laboratory buildings for this Department 
and a lecture hall to be used jointly by 
the Department and the Biological Lab- 
oratory of the Long Island Biological 
Association. This project, planned since 
1946 and under construction since Au- 
gust 1951, was finally completed in the 
spring of 1953. Formal opening ceremo- 
nies were held on May 29, and were at- 
tended by representatives of the Trustees 
and officers of the Carnegie Institution of 
Washington, the Carnegie Corporation of 
New York, and the Long Island Biologi- 
cal Association; members of that Associa- 
tion who live in the vicinity; a few of their 
friends; and the staffs of the two labora- 
tories. The group was welcomed by Mr. 
Amyas Ames, President of the Long Island 
Biological Association, who introduced M. 
Demerec, to discuss briefly the history of 
the Cold Spring Harbor laboratories, and 
Dr. Vannevar Bush, the principal speaker 
of the evening. The new laboratories were 
open for inspection, and the research staffs 
held an informal demonstration of selected 
problems representing their current work. 

A second outstanding event of the year 
was the purchase of about twenty acres of 
adjacent property from the estate of Mary 
E. Jones, one-half by the Institution and 
the other half by the Long Island Biologi- 
cal Association. The property is well 
adapted for experimental studies of a wide 
variety of plants and animals in their nat- 
ural habitats, and will be used for this 
purpose by scientists working at the lab- 
oratories. In addition, the acquisition of 



this land ensures for the laboratories the 
privacy that is essential for their efficient 
operation. 

Research 

During the past year McClintock has 
emphasized two aspects of the study of 
mutation in maize: the types of modifica- 
tion in genie expression that arise from 
changes occurring at a single locus in a 
chromosome, and the control of mutation 
at specific loci by the genotypic constitu- 
tion of the nucleus. The first of these in- 
vestigations involved examination of ap- 
proximately sixty independent alterations 
occurring at a particular locus and result- 
ing in modifications in expression of neigh- 
boring genes. These alterations are initi- 
ated by the transposable chromosomal 
unit Ds when it occupies this particular 
locus. It was found that Dominated modi- 
fications could affect the action not only of 
the known genetic factor immediately ad- 
jacent to Ds, but also of genetic factors 
known to be located four crossover units 
to the left and at least two crossover units 
to the right of it. The extent of spread 
along the chromosome of genetic change 
arising from Ds-'mduced modifications dif- 
fered in different cases. The possible range 
of this influence is difficult to determine, 
because spread of the mutational effect 
beyond the limits mentioned above incor- 
porates genetic factors whose modified 
action affects viability or functioning of 
gametes, or induces a dominantly ex- 
pressed inhibition of growth capacity. An 
additional finding of this study was that 
mutations which produce similar changes 
in phenotypic expression of known genetic 
factors may arise from dissimilar types of 



205 



206 



CARNEGIE INSTITUTION OF WASHINGTON 



modification. Such dissimilarities are de- 
tected by differences in viability of homozy- 
gote or heterozygote, in gamete function- 
ing, in crossover frequencies in the vicinity 
of the mutated factor, and in capacity for 
subsequent reverse mutation. The evidence 
suggests that no two mutation-inducing 
events at a locus are exactly alike, regard- 
less of similarities in mutational expres- 
sion of the genetic factor concerned. Evi- 
dence of genotypic control of mutational 
type has been obtained with regard to two 
of the mutable loci under investigation. In 
both cases, one particular type of mutation 
will occur in haploid nuclei that receive a 
particular genetic constitution as a conse- 
quence of meiotic segregations. In one of 
these cases, McClintock has identified a 
factor, located in a separate chromosome 
of the complement, whose presence con- 
trols the occurrence of mutation in those 
haploid nuclei receiving it. She concludes 
from this, in conjunction with evidence pre- 
viously obtained, that particular changes in 
the genetic constitution of nuclei, whether 
arising from somatic or from meiotic seg- 
regations, are responsible for controlling 
the occurrence of mutation at a number of 
mutable loci. 

Studies carried on with the bacterium 
Escherichia coli and dealing with the mech- 
anisms of spontaneous and induced mu- 
tability have been continued by Demerec, 
Hanson, Labrum, Galinsky, Hemmerly, 
and Berrie. It is reasonably certain that 
each of the specific types of change ob- 
served in these studies represents mutation 
occurring either at one locus or at a very 
few loci. The results of the past year's ex- 
periments give additional support to our 
working hypothesis regarding the origin 
of genetic changes. This hypothesis postu- 
lates that mutations are caused by some 
disturbance of the physiological function- 
ing of cells, which may occur spontane- 
ously or be induced by the action of a mu- 



tagen, and that each member of the gene 
system of a cell reacts in its own specific 
way to such a disturbance. 

Demerec and Hanson have made a fur- 
ther investigation of the phenomenon of 
mutagen stability — the fact that the degree 
of mutability of certain spontaneously mu- 
tating characters cannot be increased by 
mutagenic treatment. Tests made this year 
with an additional assortment of muta- 
genic chemicals failed to induce reverse 
mutations in the five mutagen-stable nu- 
tritional deficiencies in our collection. The 
mutagens tested now include ultraviolet 
radiation, X-radiation, and eleven chemi- 
cals. Demerec and Hanson have also 
found that bacteria grown in shaken cul- 
tures are much less sensitive to the muta- 
genic action of manganous chloride than 
are bacteria grown in aerated cultures, a 
finding which is in agreement with the 
earlier conclusion that the degree of muta- 
genic effectiveness of manganous chloride 
treatment is determined by the physiologi- 
cal condition of the treated bacterial cells. 
A further analysis of delayed effect, the 
phenomenon responsible for delay in the 
appearance of induced mutants, has shown 
that it is of widespread occurrence. Data 
concerning induction of reverse mutations 
in thirty-one cases of nutritional deficiency 
showed that delayed effect was present in 
seventeen cases. It was also found in the 
four cases of mutation involving phage 
resistance and the seven cases involving 
streptomycin resistance studied so far. 

Labrum has determined the pattern of 
delayed appearance of induced mutants 
resistant to bacteriophage T5 in bacterial 
populations maintained at different gen- 
eration times but at a constant tempera- 
ture. His results show that, regardless of 
the generation time, delayed appearance 
of induced T5-resistant mutants is char- 
acterized by an initial phase, during the 
early cell divisions, when the mutants ap- 



DEPARTMENT OF GENETICS 



207 



pear at a slow but gradually increasing 
rate. This is followed by a second phase, 
throughout which mutants appear at a 
high linear rate that is constant per unit 
time. Additional experimental evidence 
suggests that the initial slow rate of ap- 
pearance of induced mutants represents a 
true genetic delay, but that irregularity in 
the time of onset of cell division may be 
involved in the second phase, during 
which most of the induced mutants are 
manifested. 

The modifying effect of post-treatment 
on the mutagenic action of ultraviolet ra- 
diation has been studied by Galinsky and 
Berrie. Both made comparisons of fre- 
quencies of induced mutants in irradiated 
cells exposed after treatment to tempera- 
tures of 15° C and 37° C, Galinsky study- 
ing mutations to resistance to phage T3, 
and Berrie working with reversions from 
three nutritional deficiencies. Both found 
significantly lower frequencies of induced 
mutants in the 15° series, indicating the 
probability that the temperature effect, 
which was first reported by Witkin (Year 
Book No. 51, 1 951-1952, pp. 200-203), is a 
general one. Berrie was further able to 
determine that the temperature-sensitive 
period corresponds approximately to the 
first third of the first division cycle of 
treated cells. 

Hemmerly began investigations of the 
genetic effects of thermal neutrons, by de- 
termining the frequencies of revertants in 
several nutritionally deficient strains ex- 
posed for 48 or 72 hours in the nuclear 
reactor at Brookhaven National Labora- 
tory. The observed degree of mutagenic 
effect was so low that the possibility of 
gamma-ray contamination as the responsi- 
ble factor could not be excluded. 

Visconti and Symonds have investigated 
an unstable stock of bacteriophage T2, 
which forms sectored plaques. The sec- 
tors contain r mutants that differ physio- 



logically and genetically from those ap- 
pearing in wild-type stocks. The sector- 
ing is not the result of an excessive rate of 
mutation, but has been explained in terms 
of a prior mutation, which causes selection 
in favor of the r mutants during plaque 
formation. 

Last year Visconti showed that a bacte- 
rial cell can be infected twice with phage 
T2, with an interval as long as 8 minutes 
between the two infections, and still pro- 
duce phage progeny derived from both 
infections. Visconti and Garen have now 
investigated the kinetics of intracellular 
growth and recombination of phage under 
these conditions of reinfection. They find 
that the rates of growth and recombination 
are normal, and that the genetic markers 
introduced by the second infecting phage 
appear in the progeny less than 4 minutes 
after the second infection has occurred. 
The data indicate that the second infect- 
ing phage does not set up a separate intra- 
cellular vegetative pool, but instead enters 
immediately into the pool established by 
the first phage. 

The results of further attempts by Her- 
shey, Hudis, and Chase to identify chem- 
ical components of phage T2 that control 
reproduction of the virus continue to point 
to nucleic acid. Isolated virus does not con- 
tain appreciable amounts of basic protein. 
The membrane protein is metabolically in- 
ert during reproduction. Synthesis of viral- 
precursor nucleic acid occurs at times and 
rates consistent with the idea that nucleic 
acid contains the genetic determinants. 

Nucleic acid isolated by Garen from 
phage T2 has been subjected to light-scat- 
tering measurements by Dr. E. Reich- 
mann, of the Chemistry Department of 
Harvard University. The measurements 
indicate a molecular weight of about ten 
million, which corresponds to ten mole- 
cules of desoxyribose nucleic acid per 
phage particle. 



208 CARNEGIE INSTITUTION OF WASHINGTON 

McDonald has continued her studies of position. A study of the desoxyribonucleo- 

the properties of onion-root-tip desoxyri- proteins of sea urchin sperm, trout sperm, 

bonuclease. Unlike the desoxyribonuclease and calf-thymus nuclei showed that each 

previously crystallized from bovine pan- substance has unique and distinctive prop- 

creas, this enzyme does not appear to de- erties, expressive of inherent genetic differ- 

grade intracellular desoxyribonucleic acid ences. The information now available con- 

unless the cells have first been treated with cerning the individual characteristics of 

ribonuclease. Similar results are obtained these several desoxyribonucleoproteins pro- 

with the desoxyribonuclease of calf spleen, vides a favorable background for analysis 

A direct comparison of the modes of ac- of nuclear function and the mode of action 

tion of the various desoxyribonucleases of mutagenic agents. 

cannot be made, however, until they have A specific effect induced by nitrogen 

been isolated and purified. Methods are mustard in gamete nuclei of the parasitic 

now being devised for the isolation, puri- wasp Habrobracon has been studied by 

fication, and crystallization of spleen des- von Borstel. Nuclear division is blocked 

oxyribonuclease. at the sixth or seventh cleavage, and the 

Kaufmann and Das have found that so- nuclei enlarge tremendously. Cytochemical 
lutions of the enzyme ribonuclease, when analysis of the enlarged nuclei indicates 
used in treatment of root-tip cells, may act that protein synthesis continues after cleav- 
either as a narcotic, to inhibit mitosis tem- age has ceased, whereas desoxyribonucleic 
porarily; as a mutagenic agent, to produce acid synthesis does not. This suggests that 
polyploid and aneuploid chromosome com- nitrogen mustard may specifically interfere 
plexes; or as a poison, to effect pycnosis with desoxyribonucleic acid synthesis; nu- 
and death of the cell. The production of clei presumably stop dividing when a 
mitotic and chromosomal aberrations is supply of desoxyribonucleic acid building- 
associated with the degradation of ribose blocks stored in the cytoplasm is exhausted, 
nucleic acid, and this relationship em- In connection with this study it was ob- 
phasizes the significant role of ribose nu- served that chromosome synthesis and di- 
cleic acid in determining chromosome vision can occur in the partially exuded 
form and mitotic distribution. Since ribose contents of broken Habrobracon eggs, 
nucleic acid is an extremely labile struc- Such eggs will provide a favorable system 
tural component, it now seems probable for the study of nuclear division, in which 
that many of the induced abnormalities mitosis is synchronous and there are no 
effected by exposure of living cells to limiting membranes between the nucleus 
chemical and physical agents are attributa- and the environment, 
ble to alterations in their constituent ribo- 

nucleoproteins, rather than to changes in dtaff 

desoxyribonucleic acids or desoxyribonu- Evelyn M. Witkin was on leave of ab- 

cleoproteins. sence this year, and took no active part in 

Bernstein has found that the desoxyribo- the research of the Department. N. Vis- 
nucleoproteins of cell nuclei can be ex- conti, who became a junior member of 
tracted in distilled water. The physical the staff in October 1952, resigned at the 
and chemical attributes of these nucleo- end of March 1953, to return to Italy, 
proteins are unlike those of either nucleic The Department had two fellows, Rob- 
acid or protein. They are characterized by ert C. von Borstel, who worked with 
differences in solubility, viscosity, and com- Kaufmann as a Carnegie Institution Fel- 



DEPARTMENT OF GENETICS 



209 



low, and Alan Garen, who worked with 
Hershey under a fellowship from the Na- 
tional Foundation for Infantile Paralysis. 
Dr. von Borstel will leave, when his one- 
year fellowship terminates at the end of 
September, to take a research position with 
the Biology Division of Oak Ridge Na- 
tional Laboratory. Neville Symonds, in 
this country from Britain under a fellow- 
ship of the Rockefeller Foundation, has 
spent about five months at the Department 
working with Visconti and Hershey. 

Co-operative Work 

Continued close co-operation with the 
members of the Biological Laboratory has 
had a stimulating effect on research at the 
Department. The five members of the 
Laboratory staff took part in our weekly 
staff meetings for discussion of current 
research; and both they and their assistants 
attended our weekly seminar lectures and 
participated in the regular meetings for 
review of current literature. Year-round 
research at the Biological Laboratory is 
focused on genetical problems related to 
those studied at this Department. V. Bry- 
son, W. Szybalski, and L. H. Geronimus 
are working with bacteria; and B. Wallace 
and J. C. King use Drosophila in their 
studies. 

Our staff members profited also by asso- 
ciation with other research workers who 
stayed at the Biological Laboratory for 
various periods during the year. These 
included the following scientists: William 
Hayes, of the University of London; Frank 
Fenner, of the Australian National Uni- 
versity; W. Weidel, of the Max Planck- 
Institut fiir Biologie, Tubingen, Germany; 
J. D. Watson, of the Cavendish Labora- 
tory, Cambridge, England; Max Delbrikk, 
of the California Institute of Technology; 
S. E. Luria, of the University of Illinois; 
Mark Adams, of New York University 



College of Medicine; E. D. DeLamater, of 
the University of Pennsylvania School of 
Medicine; E. Caspari, of Wesleyan Uni- 
versity; I. Gersh, of the University of Chi- 
cago School of Medicine; D. Shemin, of 
the College of Physicians and Surgeons, 
Columbia University; and J. Armstrong, 
of the American Museum of Natural 
History. 

Members of our stafT have co-operated 
in various ways with scientists at other 
institutions, particularly members of the 
Brookhaven National Laboratory at Up- 
ton, New York. Kaufmann collaborated 
with Dr. M. J. Moses, Mr. W. A. Higin- 
botham, and Mr. R. Chase of that Labora- 
tory in working out numerous problems 
connected with an effort to adapt the RCA 
television camera for use in cytological 
research. During the summer of 1953, 
McClintock grew her experimental corn 
at Brookhaven in co-operation with Dr. 
W. R. Singleton. Demerec and Hemmerly 
exposed bacteria to thermal neutron radia- 
tion in the nuclear reactor at Brookhaven. 
Kaufmann also co-operated with Dr. T. F. 
Anderson, of the Johnson Foundation of 
the University of Pennsylvania, in elec- 
tron microscope studies. 

Meetings and Lectures 

The Eighteenth Cold Spring Harbor 
Symposium on Quantitative Biology, held 
early in June under the auspices of the 
Biological Laboratory, brought together 
about 270 scientists interested in basic as- 
pects of research with bacterial, plant, and 
animal viruses. Thirteen of the partici- 
pants were from abroad. 

At various times throughout the year, 
members of the staff were invited to dis- 
cuss their research in seminar meetings 
with other groups. Demerec spoke at a 
joint seminar with the Department of 
Zoology of Columbia University, held at 



210 



CARNEGIE INSTITUTION OF WASHINGTON 



Cold Spring Harbor; Kaufmann spoke at 
Smith College, Hofstra College, and 
Brown University; and Hershey at the 
University of Colorado Medical Center, 
as well as the Cold Spring Harbor Sym- 
posium. 

Other Activities 

For the eighteenth year Demerec com- 
piled and edited Drosophila Information 
Service, a mimeographed bulletin prepared 
at this Department from the contributions 
of Drosophila research workers in all parts 
of the world. The directory section of the 
November 1952 issue listed 124 laboratories 



and 577 research workers co-operating in 
the project. A similar circular for geneti- 
cists working with microorganisms, Micro- 
bial Genetics Bulletin, was compiled and 
edited for the fourth year by Witkin. 

The Drosophila Stock Center, under the 
care of Mrs. G. C. Smith, sent out a total 
of 1291 cultures to research and teaching 
laboratories. Of these, 172 cultures were 
shipped to Europe, Asia, Australia, and 
South America. 

The Department's library, with Mrs. H. 
H. Wheeler in charge, acquired 193 books 
during the year, and received 325 periodi- 
cals and serial publications. 



BACTERIAL GENETICS 

M. Demerec, E. L. Labrum, I. Galinsky, }. Hemmerly, A. M. M. Berrie, J. Hanson, 

I. Blomstrand, and Z. Demerec 



In our studies of the mechanism of 
spontaneous and induced mutability we 
are working with specific types of genetic 
change in strain B of Escherichia coli, each 
of which, we are reasonably certain, repre- 
sents mutations occurring at either one lo- 
cus or not more than a few loci. Our earlier 
work revealed several phenomena, some 
of them still unique in the genetic litera- 
ture. These phenomena are mutagen sta- 
bility, delayed effect, mutagen specificity, 
and modifications of mutagenic effective- 
ness. During the past year we continued 
with studies of the mechanisms responsible 
for these aspects of mutational behavior. 
We made further investigations of muta- 
gen stability, testing our five mutagen- 
stable types with nine chemicals that have 
generally proved to be potent mutagens 
for our material; but none of these was 
effective in inducing reversions of the five 
deficiency types. We found that the muta- 
genic effect of manganous chloride is con- 
siderably less in bacteria grown in shaken 
cultures than in bacteria grown in aerated 
cultures. Our studies of the delayed effect 
showed that it is a widespread but not uni- 



versal phenomenon, and also that it can be 
detected and quantitatively studied with 
the chemostat, using a continuously grow- 
ing culture. Finally, we made an extensive 
study of the effects of low-temperature 
post-treatment on the mutagenic action of 
ultraviolet radiation. Work was also be- 
gun to determine whether or not mutation 
can be induced in E. coli by treatment 
with thermal neutrons. 

In addition to the workers named above, 
our group included Mrs. G. C. Smith, 
who had charge of the Drosophila colony, 
and Mrs. Katherine M. Main and Mrs. 
Jean W. Mclntyre, who washed and steri- 
lized the glassware used in work with 
bacteria. 

Our work received partial support from 
a grant-in-aid from the American Cancer 
Society on recommendation of the Com- 
mittee on Growth of the National Re- 
search Council. 

Mutagen Stability 

In our report two years ago (Year Book 
No. 50, 1950-1951, pp. 184-185) we de- 
scribed the finding that in certain sponta- 



DEPARTMENT OF GENETICS 



211 



neously mutating types the rate of muta- 
tion could not be increased by treatment 
with mutagens. At that time we had two 
mutagen-stable genes, which had been 
tested with ultraviolet radiation, manga- 
nous chloride, and (3-propiolactone. Last 
year we mentioned the discovery of three 
additional mutagen-stable genes, making a 
total of five, among 35 nutritional deficien- 
cies that we had investigated. During the 
past year Demerec and Hanson, in experi- 
ments with a number of additional muta- 
genic agents, have found that none of them 
is capable of increasing mutation rate in 
these mutagen-stable types above the spon- 
taneous level. So far, the following muta- 
gens have been tested: ultraviolet rays, 
X-rays, manganous chloride, ferrous chlo- 
ride, (3-propiolactone, acriflavine, formal- 
dehyde, hydrogen peroxide, neutral red 
with light, and four aromatic nitrogen 
mustard compounds, namely, NN-di-(2- 
chloroethyl)-/7-toluidine (R44), NN-di-(2- 
chloroethyl)-/7-anisidine (R45), 1 :3-dimeth- 
anesulphonoxypropane (GT40), and 1:4- 
dimethanesulphonoxybut-2-yne (GT58) . 

It has been found that strains carrying 
mutagen-stable genes are not themselves 
immune to the effect of mutagens, as is 
shown by the fact that a treatment which 
does not affect a mutagen-stable deficiency 
is effective in inducing mutations of other 
characters in the same strain. For ex- 
ample, in a strain (Sd-4-88) carrying both 
streptomycin dependence and a mutagen- 
stable histidine deficiency, the Sd-4 char- 
acter reacts to treatment with mutagens in 
the same way as does Sd-4 m other strains 
that do not carry the mutagen-stable gene. 
Similarly, tests for mutation to phage re- 
sistance can be made in all our strains car- 
rying mutagen-stable deficiencies; and 
these tests, as far as they have been carried 
out, show that the locus responsible for 
resistance to Ti reacts to mutagens in the 
same way in strains carrying a mutagen- 



stable gene and in strains not carrying 
such a character. It is therefore evident 
that mutagen stability is a property of 
certain genes rather than of certain strains. 
Of the five mutagen-stable types we now 
have, one (tryptophaneless 12-22) mutates 
spontaneously with a frequency of about 
6 X io -11 , which is the second lowest spon- 
taneous-mutation frequency found among 
our 37 nutritional deficiencies; whereas 
another (prolineless 12-100) mutates spon- 
taneously with a frequency of about 2.9 X 
io~ 8 , the second highest spontaneous fre- 
quency in this collection of strains. The 
other three have intermediate spontaneous 
mutability; histidineless 12-23 anQl niethio- 
nineless-threonineless 12-66 mutate with a 
frequency of 4 X io -10 , and histidineless 
R4-88 with a frequency of 5.5 X io -9 . Thus 
it is evident that mutagen stability in these 
types is not related to their rates of spon- 
taneous mutation. 

Modification of Mutagenic Effective- 
ness of Manganous Chloride 

Our earlier studies had shown that the 
degree of mutagenic effectiveness of man- 
ganous chloride treatment is influenced by 
several factors that affect the physiological 
condition of the treated bacterial cells. We 
had found the frequency of induced mu- 
tants to be almost 10 times higher in bac- 
teria grown before treatment in aerated 
cultures, which usually reach a concentra- 
tion of about 2Xio 9 /ml, than in bacteria 
grown in nonaerated cultures, which usu- 
ally reach a concentration of about 2X10 8 
/ml. A difference in response had also 
been observed between bacteria treated 
with MnCl 2 in the resting stage and those 
treated in the growing stage — growing 
bacteria being less affected by the same 
treatment. 

When we moved into new laboratories 
this year, an incubator room became avail- 
able to us, and it appeared more con- 



212 



CARNEGIE INSTITUTION OF WASHINGTON 



venient to aerate the growing bacterial cul- 
tures by shaking than by bubbling, par- 
ticularly since the experience of other 
workers had indicated that bacteria in 
shaken cultures reach an even higher con- 
centration. Unexpected results were ob- 
tained, however, in the experiments with 
MnCl 2 being carried on by Demerec and 
Hanson, and the difference was traced to 
this substitution of shaking for aeration 
in growing the cultures. A comparison 
was then made of effect of MnCl 2 treat- 
ment on bacteria previously grown in 
tightly closed bottles in a shaker and bac- 
teria previously grown in aerated cultures, 
using strains representing eight nutritional 
deficiencies and streptomycin dependence. 
The number of induced mutations was 4 
to 50 times higher in the aerated bacteria 
than in the bacteria grown in the shaker. 
Thus bacteria grown in tightly closed bot- 
tles in a shaker, which reach a concentra- 
tion even higher than that of bacteria 
growing in aerated cultures, still show a 
closer resemblance, in their reaction to 
MnCl 2 treatment, to bacteria grown with- 
out aeration, which do not reach so high 
a concentration. 

Occurrence of the Delayed Effect 

The "delayed effect" was discovered 
seven years ago, when it was noted that 
ultraviolet- or X-ray-treated cells of E. colt 
had to pass through ten to twelve divisions 
before the total number of phage-resistant 
mutants induced by the treatment could be 
manifested. Since that time, it has been 
found that this delay in appearance of in- 
duced mutants is a widespread, although 
not a universal, phenomenon. An analysis 
of induced reversions of nutritional defi- 
ciencies in our collection, made by Deme- 
rec and Hanson, has demonstrated the de- 
layed effect in 17 out of 31 cases tested, or 
about 55 per cent. In the other instances, 



all the induced mutants appeared after one 
division. The delayed effect has also been 
found in all the cases of mutation involv- 
ing phage resistance (4) and streptomycin 
resistance (7) that have been studied. 

Certain of our observations — that the de- 
layed effect is evident in only about 50 per 
cent of nutritional mutations, that each 
locus has its own pattern of behavior, and 
that more than one pattern of behavior can 
be analyzed in the same batch of treated 
cells — eliminate the possibility that the de- 
layed effect is caused by a multinucleate 
condition of cells, or by diploidy, poly- 
ploidy, multiple-strand chromosomes, com- 
posite genes, or variability in the onset of 
division of treated cells. On the basis 
of what is known at present, there are 
two possible mechanisms that could be 
responsible for the delayed effect; and it 
appears likely that both of them operate, 
to various extents, in different cases. These 
mechanisms are (1) induced instability of 
a gene, which persists through several cell 
divisions (a metastable condition), and 
(2) phenotypic lag, that is, delay in ap- 
pearance of the phenotype because of the 
continued presence in the cell of some sub- 
stance produced by the gene before it 
mutated. 

Generation Time and the 
Delayed Effect 

Previous studies by Demerec (Year 
Book No. 51, 1951-1952, pp. 194-196) sug- 
gested that the pattern of delayed appear- 
ance of induced mutants is determined by 
the particular genetic locus involved and 
is unaffected by the kind of mutagenic 
agent used. Witkin's investigation (Year 
Book No. 51, pp. 200-203) of the effect of 
temperature on rates of spontaneous and 
induced mutation and on delayed appear- 
ance of ultraviolet-induced Ti-resistant 
mutants in strain B/r suggested an inti- 



DEPARTMENT OF GENETICS 



213 



mate relation between cell division and 
the rates of appearance of both spontane- 
ous and induced mutants. The work of 
Novick and Szilard with the chemostat 
showed that the rate of spontaneous muta- 
tion to phage T5 resistance in strain B/it/f 
of E. coli is independent of the rate of 
cell division. As a result of this finding 
and Witkin's observations, Labrum in- 
vestigated the pattern of delayed appear- 
ance of mutants in bacterial populations 
maintained at different generation times 
but at the same temperature after treat- 
ment with a mutagenic agent. 

In these experiments the division rate of 
cells was varied by two different methods. 
The first was the use of chemostats and 
the second the use of two different solid 
media. The tryptophane-requiring strain 
B/it/f was used throughout the investiga- 
tion. The mutation system studied was 
the change from sensitivity to resistance 
to coliphage T5. 

Experiments with the chemostat. The 
chemostat designed by Novick and Szilard 
at the University of Chicago is a continu- 
ous-flow device that maintains a popula- 
tion of bacteria, dividing at a constant re- 
duced rate, for an indefinite period. When 
one essential nutrient is present at a limit- 
ing concentration in the medium, the gen- 
eration time of bacteria dividing in the 
chemostat can be controlled by the flow 
rate of fresh medium from the storage 
tank into the growth tube. 

In these experiments a synthetic lactate 
medium was used, with tryptophane as the 
controlling growth factor. Cells treated 
with the mutagenic chemical MnCl 2 were 
inoculated into each of three chemostats 
adjusted so that the generation time was 
different for each dividing population. At 
frequent intervals samples were taken 
from each population and analyzed, by 
the usual plating techniques, for number 
of viable cells per milliliter and for fre- 



quency of T5-resistant mutants. Three ex- 
periments were performed at different 
times, with essentially the same results. 
No correction was necessary for spontane- 
ous mutations, since they did not contrib- 
ute significantly to the observed increase 
in mutant frequency during the time re- 
quired for these experiments. 

In figure 1 the results of a typical experi- 
ment are presented graphically. The fre- 
quencies of MnCl 2 -induced T5-resistant 
mutants in each of the three populations 
are plotted arithmetically as a function of 
generations. Each curve is characterized 
by an initial portion representing a period 
during which the induced mutants ap- 
peared at a slow but gradually increasing 
rate. This was followed by a period dur- 
ing which the bulk of induced mutants 
appeared at a linear rate until the total 
yield of mutants was approached. From a 
comparison of the slopes of the linear por- 
tions of the three curves it is evident that 
the rate of appearance of induced mutants 
was most rapid in the population that had 
the longest generation time (10 hours, 47 
minutes), and slowest in the population 
with the shortest generation time (1 hour, 
50 minutes). 

In figure 2 the data from the same exper- 
iment are plotted as a function of time. In 
this case it can be seen that the rates of 
appearance of induced mutants are ap- 
proximately the same throughout the lin- 
ear portions of the three curves. The fact 
that the three curves do not coincide is due 
to differences in length of the periods of 
initial slow rate of appearance. 

Experiments with solid media. The 
phage-spraying technique developed by 
Demerec has proved to be an invaluable 
method for the study of delayed appear- 
ance of induced mutants in E. coli. There- 
fore experiments were designed with a 
view to confirming the essential findings 
of the chemostat studies by use of the 



214 



CARNEGIE INSTITUTION OF WASHINGTON 




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2l6 



CARNEGIE INSTITUTION OF WASHINGTON 



spray technique. The same B/it/f strain 
was used, and T5-resistant clones were 
scored. 

The method consisted essentially in plat- 
ing a known number of MnCl 2 -treated 
cells onto a solid medium, allowing the 
bacteria to pass through a certain number 
of divisions, and then spraying the plates 
with an aerosol of a suspension of phage 
T5 to determine the number of T5-resist- 
ant clones. The generation time was 
varied by plating the MnCl 2 -treated cells 
onto two different kinds of solid medium. 
One was nutrient agar supplemented with 
1 per cent dextrose; the other was the same 
synthetic lactate medium used in the chem- 
ostat experiments with tryptophane added 
in a concentration of 20 ng/m\. The gen- 
eration times of strain B/it/f on the two 
media were 18 minutes and 55 minutes, 
respectively. The temperature was 37° C 
for all incubation periods. The rates of 
spontaneous mutation on the two media 
were determined by the same techniques. 
All induced-mutant frequencies were then 
corrected for spontaneous mutations. 

In figure 3 the frequencies of T5-resist- 
ant clones per io 8 plated bacteria are 
plotted arithmetically as a function of gen- 
erations. The resulting curves show the 
same general characteristics as those repre- 
senting the results of the chemostat experi- 
ments (fig. 1) : an initial slow rate of ap- 
pearance of induced mutants, followed by 
an increased rate that appears to be linear 
until it approaches total expression. The 
slopes of the linear portions of the curves 
are not the same, indicating that the rates 
of appearance of induced mutants per cell 
per generation were different on the two 
different media. It should also be noted 
that the total yield of induced mutants was 
doubled when the bacteria were plated on 
lactate medium. This effect of nutrition 
on the total number of induced mutants 
manifested was not investigated further. 



In figure 4 the same data are plotted as 
a function of absolute time. The length of 
the lag phase, which was i l / 2 hours on 
nutrient agar plus dextrose and 2 hours 
on lactate agar, was deducted from all 
the plotted times. The resulting curves 
are again comparable with those obtained 
in the chemostat experiments (fig. 2), in 
that they show a constant rate of appear- 
ance of induced mutants per unit time 
during the period represented by the linear 
portions of the curves. 

It has been suggested that irregularity 
in the time of onset of division of individ- 
ual bacterial cells may play an important 
role in the delayed appearance of induced 
mutants. An experiment suggested by Dr. 
Aaron Novick was performed to test this 
point. MnCl 2 -treated B/it/f cells were 
inoculated into a flask of sterile, liquid 
lactate medium supplemented with tryp- 
tophane (20 ug/ml), so that there was ap- 
proximately 1 cell per 3 ml of medium. 
One ml of the inoculated medium was dis- 
pensed into each of 295 glass tubes, which 
were incubated for 20 hours. After the in- 
cubation period a pour plate with nutrient 
agar was prepared from the contents of 
each tube, and the plates were incubated 
for 48 hours. At the end of that time there 
were 201 plates without colonies and 94 
plates with one or more colonies. Thus it 
appeared probable that most of the cul- 
tures showing growth had started with a 
single cell. On the basis of colony counts, 
the cultures were grouped according to 
the approximate number of divisions ac- 
complished in each (table 1). 

Since the lag phase for B/it/f in liquid 
lactate had previously been found to be 
about 10 hours, and the generation time 
1 hour, the predicted number of genera- 
tions after a 20-hour incubation period was 
ten. The results shown in the table indi- 
cate that about 72 per cent of the cultures 
had passed through eight to twelve divi- 



DEPARTMENT OF GENETICS 



217 



sions. In other words, a majority of the 
cells had begun to divide at the expected 
time (plus or minus two generation times) . 
Further experiments of this type, using 
cultures started from single cells, are neces- 
sary to define more clearly the relation be- 
tween differences in time of onset of divi- 
sion of individual cells and delayed appear- 
ance of induced mutants. 

From the results of this investigation it 
was concluded that the delayed appearance 

TABLE 1 

Distribution of single-cell cultures accord- 
ing to number of divisions accomplished 

IN 20 HOURS 
Generations No. cultures 

6 

1 3 

2 1 

3 ° 

4 2 

5 3 

6 4 

7 7 

8 22 

9 J 5 

10 18 

11 10 

12 3 

of induced T5-resistant mutants in strain 
B/it/f of E. coli is characterized by two 
distinct phases. The first phase, in which 
mutants appear at a slow rate, occurs dur- 
ing the early cell divisions; it is followed 
by a second phase, in which induced mu- 
tants appear at a high linear rate that is 
constant per unit time. The results of the 
experiment using cultures started from 
single cells suggest that the initial phase 
represents a true genetic lag, which can- 
not be accounted for by differences in the 
time of onset of cell division, and that the 
length of the lag period depends at least 
partly on the generation time. The second 



phase, however, during which the bulk of 
induced mutants is manifested at a linear 
rate, may possibly be accounted for by the 
finding that there was a four-generation 
range in number of divisions completed, in 
a majority of the cultures started from 
single cells. 

Effects of Temperature on Spontaneous 
and Induced Mutation 

Last year (see Year Book No. 51, 1951- 
1952, pp. 198-203) Witkin reported that 
post-treatment with low temperature fol- 
lowing ultraviolet treatment reduced the 
frequency of mutants resistant to phage Ti 
induced by the irradiation. The frequency 
of spontaneous mutants was not affected 
by the cold treatment. 

Galinsky this year undertook a series 
of similar experiments, testing the effects 
of exposure to the two temperatures, 37° C 
and 15 ° C, on both spontaneous and in- 
duced mutability to resistance to phage T3. 
In the induced-mutation experiments, bac- 
teria were treated with either ultraviolet 
light or MnCl 2 , plated, and then incubated 
at either 15 ° or 37°. 

The frequency of spontaneously occur- 
ring T3-resistant mutants on plates ex- 
posed to 15 ° was found to be about 30 per 
cent of the frequency on those kept at 37°. 
This differs from Witkin's results with 
Ti-resistant spontaneous mutants, which 
showed no variation in frequency at the 
two temperatures. 

The effect of temperature on ultraviolet- 
induced mutation to T3 resistance is as 
follows. The final yield of ultraviolet-in- 
duced mutations in material incubated at 
37° after irradiation is about 400,000 per 
io 8 cells surviving treatment, and is com- 
pletely manifested in about nine genera- 
tions. The final yield in material exposed 
to 15 ° is about 300,000 per io 8 , and is 
reached in about eleven generations. When 



2i8 CARNEGIE INSTITUTION OF WASHINGTON 

the results are plotted as percentages of the act differently to the same post-treatment 

final yield of induced mutations as a func- condition. 

tion of post-irradiation divisions at 37° and Differential response to the mutagenic 
at 15 °, the two curves run parallel for action of ultraviolet light in bacteria ex- 
most of their length. The 15 ° curve, how- posed after irradiation to temperatures of 
ever, has a longer toe portion than the 37° 15 ° C and 37° C has been studied further 
curve. This may account for the fact that by Berrie. The mutation systems utilized 
with 15 ° post-treatment it takes almost by him were reversion from amino acid 
two generations longer for the total num- deficiency (leucineless 12-57, and proline- 
ber of induced mutants to be manifested, less WP-14) and reversion from strepto- 

Treatment with MnCl 2 and subsequent mycin dependence (Sd-4). Other defi- 

incubation at 37° results in a total yield of ciency types were subjected to preliminary 

about 500,000 T3~resistant mutants per io 8 analysis, and all showed indications of 

survivors, reached in about nine genera- responding in the same fashion as 12-57, 

tions. If the bacteria are exposed to 15 ° WP-14, and Sd-4, DUt tnev did not have 

temperature after MnCl 2 treatment, then suitable properties for rigorous experi- 

a final number of about 150,000 mutants mental work. 

per io 8 is produced, also in about nine Once it had been established that the 
generations. When the results are plotted temperature effect is of widespread occur- 
on semi-logarithmic paper in terms of rence, the relation between ultraviolet dose 
logarithms of induced mutants per io 8 and induced mutation, with 15 ° and 37° 
viable bacteria against number of divisions, post-treatment, was determined for strains 
the two curves are superimposed until 12-57, WP-14, an d Sd-4. The procedure 
about the fifth generation, after which they was standard for all three strains, and con- 
separate to their respective levels. The sisted in growing a culture in aerated broth 
end-point number at 15° is about 30 per (with the addition of 10 \ig of strepto- 
cent of the yield at 37°. mycin per milliliter in the case of Sd-4) 

These experiments have shown that low- until the cells were in a resting state, wash- 
temperature treatment decreases the num- ing with saline, suspending in saline, ir- 
ber of mutations, both spontaneous and in- radiating with a known dose of ultra- 
duced, to resistance to phage T3, and also violet at room temperature, and plating 
that the temperature effect is different in onto a medium that would select the in- 
ultraviolet-treated and MnCl 2 -treated bac- duced revertants. The plates were pre- 
teria. In the former, 15 ° post-treatment heated and precooled. Low-temperature 
brings about a comparatively small reduc- treatment consisted in keeping the plated 
tion in the final number of mutants, but material at a temperature of 15 ° for 30 
a much slower rate of appearance during hours before allowing it to complete 
the first five divisions; whereas in MnCl 2 - growth at 37°. 

treated material the cold post-treatment Table 2 shows the frequencies of mu- 
effects a decided reduction in the final tants induced in the three strains by ultra- 
number of mutants, although there is no violet doses in the range 100 to 700 ergs/ 
change in the numbers manifested per gen- mm 2 with post-treatment at the two tem- 
eration during the first five divisions. This peratures. In all three strains the tempera- 
seems to indicate that the mutagenic proc- ture effect is manifested over most of this 
esses resulting from ultraviolet and MnCl 2 range of dosage. In strain 12-57, t ^ ie e ^ ect 
treatment are not identical, since they re- ceases at about 600 ergs/mm 2 ; in the other 



DEPARTMENT OF GENETICS 



219 



two, low-temperature treatment after ir- 
radiation with the higher doses is less 
effective in reducing the frequency of in- 
duced mutants. With doses of more than 
700 ergs/mm 2 , the high degree of killing 
makes the results less significant; but we 
have fairly good evidence from a number 
of experiments that the temperature effect 
is not present at these high doses. Witkin 
was able to demonstrate an effect at 800 
ergs/mm 2 , using the B/r strain of E. coli; 
but this result may be explained by the 
fact that her material was grown in syn- 



different; for example, a dose of 100 ergs/ 
mm 2 produces only 40 mutants per io 8 
survivors in leucineless 12-57, ^ ut 54^° P er 
io 8 in prolineless WP-14. When cells are 
kept at 15 ° for 30 hours after irradiation, 
a smaller number of reversions is induced 
for any given ultraviolet dose, except in 
leucineless 12-57 at tne highest doses used. 
An attempt was made to identify the 
period of the growth cycle during which 
temperature can affect the mutagenic ac- 
tion of ultraviolet. The general procedure 
was similar to that already described; irra- 



TABLE 2 

Frequencies of mutants per io 8 survivors induced by given doses of ultraviolet radiation 
followed by exposure to temperatures of 15° c and 37° c 



Dose (ergs/mm 2 ) 



Strain Post-treatment 

100 

12-57 15° C 32' 

37° C 40 

Sd-4 15° C 468 

37° C 1,303 

WP-14 15° C 779 

37° C 5,480 



200 



300 



400 



500 



600 



700 



39 


53 


152 


528 


1,584 


3,590 


121 


269 


472 


786 


1,342 


1,922 


836 


1,233 


1,076 


3,030 


5,213 


6,543 


,980 


3,803 


4,673 


7,216 


8,913 


15,900 



1,573 1,605 



1,577 



4,463 



8,440 22,300 



8,154 10,980 17,930 26,000 34,000 31,000 



thetic medium before irradiation. Galin- 
sky has found that the tolerance of B/r 
to ultraviolet radiation is greatly increased 
if the bacteria are grown in synthetic 
medium instead of nutrient broth. For 
the strains used here, synthetic medium is 
not suitable. 

Within the range of doses used in these 
experiments there is a proportional increase 
in frequency of induced mutants as the 
ultraviolet dose increases, but the manner 
of increase is different when irradiated 
cells are kept at 15 ° rather than at 37°. 
With 37° incubation, the frequency of in- 
duced mutants increases almost linearly up 
to about 600 ergs/mm 2 , and then levels off. 
This linear increase is characteristic of all 
the strains, but the quantitative response is 



diation was at a standard dose of 400 ergs/ 
mm 2 , and the length of time the cells 
were exposed to 15 ° before transfer to 37° 
was much shorter. From these experi- 
ments it was found that low temperature 
can lower the frequency of induced mu- 
tants if the cells are exposed to 15 ° for 10 
hours. This is about one-third of the lag 
phase. 

The temperature-sensitive period at 37° 
was determined by keeping irradiated cells 
for short intervals at 37° before transfer to 
15 ° for 30 hours. (These were subse- 
quently incubated at 37° for four days to 
complete growth.) The length of the tem- 
perature-sensitive period is about i l / 2 hours, 
or, again, one-third of the lag phase. Thus, 
although the temperature-sensitive period 



220 CARNEGIE INSTITUTION OF WASHINGTON 

is of different duration at 37° and at 15°, extremely effective in inducing chromo- 

it amounts to the same fraction of the somal aberrations in higher organisms, 

lag phase at the different temperatures. These neutrons have very low energy and 

Further experiments indicated that this velocity; and their biological activity is 

temperature-sensitive period corresponds to largely due to their capture by atoms in the 

the first part of the lag phase. exposed cells, and the subsequent emission 

It was more convenient to carry out of gamma rays, protons, and alpha rays, 
some of the experiments with liquid cul- In order to determine whether thermal 
tures; and it was found that cells kept in neutrons would induce mutations in E. 
synthetic medium showed a 75 per cent coli, Hemmerly studied reversions to non- 
lower frequency of induced mutants than deficiency in a number of nutritionally 
those kept in the same medium enriched deficient strains exposed to this radiation, 
with 0.01 per cent nutrient broth. This Five of the deficiencies were mutagen 
phenomenon cannot be evaluated until stable; that is, it had previously been ascer- 
more critical studies have been made. tained that their rate of reversion to nutri- 

The existence of the temperature effect, tional independence could not be increased 

in itself, is sufficient to suggest that ultra- over the spontaneous rate by treatment 

violet radiation acts indirectly to produce with mutagenic agents, 

mutation. Further evidence is provided by The strains to be tested were grown in 

the shape of dose-mutation curves based broth, washed, and resuspended in a syn- 

on the data for 15 ° and 37° post-treatment thetic medium lacking glucose. Two-ml 

shown in table 2. They lead us to conclude samples of the washed bacterial suspension 

that more than one reaction is responsible were placed in cellulose nitrate tubes with 

for the final mutation. The fact that the Lucite caps. They were then exposed to 

37° curve is approximately linear might radiation in the thermal column of the 

indicate a zero-order reaction, or a one-hit nuclear reactor at Brookhaven National 

phenomenon, with only one participant in Laboratory for various periods of time, 

the reaction. The shape of the 15 ° dose- Control tubes were kept under the same 

mutation curve is that expected from a conditions except for the exposure to ra- 

reaction of higher order, in which more diation. 

than one reactant participates. The line- Extremely long periods of exposure 
arity of the 37° curve probably reflects a were requ ired to obtain any mutagenic 
high degree of integration among the ef j ect> After ^ hours in the thermal col- 
various reactions that proceed in ultra- umn? WP-14, the most sensitive strain, 
violet mutagenesis. At 15 ° this integration showed a frequency of induced mutants 
is upset, and the yield of mutants depends o£ about 2000 per I0 s surv i v i ng bacteria, 
on the rate of the process most affected. Th i s i s l 0W er than the frequency obtained 
The studies just described have produced after a dose f only I00 er gs/mm 2 of ultra- 
no evidence about the nature of these in- violet lig ht. Two strains, M-3 and Sd-4-55, 
termediate reactions. were tested after 72 hours of exposure. 

Only the streptomycin-dependence locus of 

Studies with Thermal Neutrons strain sd _ 4 „ 55 sn0W ed an increase in in- 

Relatively little has been done to study duced mutation. There was no increase in 

the genetic effects of thermal neutrons, induced reversion from tryptophane defi- 

although it has been shown that they are ciency in the same strain. The five muta- 



DEPARTMENT OF GENETICS 



221 



gen-stable deficiencies showed no response 
to the irradiation, regardless of the length 
of time of exposure. 

The long period of exposure necessary 
to produce any appreciable mutagenic ef- 
fect, and the low degree of this effect, sug- 
gest the possibility that the thermal neu- 
trons themselves do not act as a mutagenic 
agent. One possible source of mutagenic 
activity is gamma-ray contamination in 
the thermal column. This contamination 
amounts to about 50 r per hour. It is 
planned to treat these strains with small 
doses of X-rays in order to determine 
whether the extent of induction of muta- 



tions observed in the experiments can be ac- 
counted for on the basis of the contaminat- 
ing radiation. 

At present it cannot be definitely con- 
cluded that the induced mutants observed 
were the result of thermal neutron irradia- 
tion. Regardless of the nature of the 
mutagenic agent, however, it should be 
noted that each gene responded to it in a 
specific manner. These results agree with 
the observations of Demerec, Hanson, and 
Monsees (Year Book No. 51) regarding 
the specific responses of nutritionally defi- 
cient strains to treatment with ultraviolet 
radiation, MnCl 2 , and (3-propiolactone. 



GENETIC STUDIES WITH BACTERIOPHAGE T2 

N. Visconti, A. Garen, and N. Symonds 



Unity of the Vegetative Pool in Phage- 
Infected Bacteria 

A considerable body of genetic and 
chemical facts has led to the following in- 
terpretation of the growth cycle of phage 
T2. On infecting a bacterial cell, a phage 
particle is transformed into a noninfective 
intracellular form called vegetative phage. 
This vegetative form can multiply and, if 
a bacterium has been infected with a mix- 
ture of two or more related phages that 
differ in their genetic composition, can also 
undergo genetic recombination. During 
the first few minutes after infection, called 
the eclipse period, only vegetative particles 
are present within the bacterium. After- 
ward, infective (or mature) particles be- 
gin to form and accumulate at a constant 
linear rate until the bacterium lyses, at 
which time several hundred mature phage 
progeny are liberated. The vegetative par- 
ticles are pictured as forming an intracel- 
lular pool from which units are removed 
at random and transformed irreversibly 
into mature phage particles, which then 
remain inert with respect to the multipli- 
cation and recombination processes of the 



vegetative particles. Thus the three critical 
processes that are assumed to be operating 
during phage growth are multiplication, 
recombination, and maturation of vegeta- 
tive particles. 

Recently Visconti found that it is pos- 
sible to reinfect a cell as late as 8 minutes 
after the primary infection if a very high 
dose of reinfecting phage (around 1500 
particles per cell) is used. Using phage 
T2 labeled with different genetic markers 
for the two infections, he showed that the 
reinfecting phage type was represented in 
the progeny, and that all the recombinant 
types were also present in the proportions 
to be expected in mixed infections with 
unequal amounts of parental phage. This 
discovery leads to an additional question 
about the properties of the intracellular 
pool of vegetative particles, namely, 
whether or not the late-infecting phage 
will enter immediately into the vegetative 
pool already established by the first phage. 
To answer this question, Visconti and 
Garen determined the rates of formation 
of mature phage T2 when a bacterium is 
subjected to two successive infections, with 



222 



CARNEGIE INSTITUTION OF WASHINGTON 



an interval of 6 or 8 minutes between in- 
fections. Since phages labeled with differ- 
ent genetic markers at two loci were used 
(T2rk for the first infection, T2r + h + for 
the second), it was possible to follow indi- 
vidually the formation of phage progeny 
derived from both infections. Our data 
reveal the following facts: 

1. Reinfection of a bacterium after 6 or 
8 minutes does not interfere with the nor- 
mal growth processes of the first infecting 
phage. 

2. The genetic markers introduced by 
the reinfecting phage appear in the prog- 
eny (both as parental and as complemen- 
tary recombinant types) at the end of the 
normal eclipse period of 12 minutes, and 
thereafter accumulate at the normal rate. 
This is also true when the reinfecting 
phage has been inactivated by ultraviolet 
light. Since reinfection can occur as late 
as 8 minutes after the first infection, we 
have the phenomenon of formation of new 
progeny less than 4 minutes after the pa- 
rental phage has infected a bacterium. 

3. The complementary recombinant 
types (r + h and rh + ) are produced in equal 
numbers throughout the period when ma- 
ture progeny appear. Also, the ratio of 
recombinant to parental-type progeny dur- 
ing this period is the expected one for 
mixed infections in which both parents 
can multiply and recombine on an equal 
basis. Under the conditions described, the 
second phage behaves as the minority par- 
ent in most of the bacteria. 

These results are readily interpreted in 
terms of an intracellular pool of vegetative 
phage particles. We picture the first infect- 
ing phage as establishing the pool. The 
reinfecting phage then finds the pool avail- 
able and enters immediately. Since the 
pool has probably been partly filled by the 
multiplication of the first phage before re- 
infection, and only a few of the reinfecting 
particles are able to enter the cell, the 



second phage is in the minority. But once 
it has entered the pool, the second phage 
can participate in the multiplication and 
recombination processes of the vegetative 
particles on an equal basis with the first 
phage. Consequently, the events that fol- 
low reinfection are the same as if the two 
infections had occurred simultaneously 
with unequal numbers of the two parental 
types. Thus we conclude that reinfecting 
phage (either viable or ultraviolet-inac- 
tivated) shares a common vegetative pool 
with the primary infecting phage, and that 
the time constants of recombination and 
maturation are characteristic of the pool, 
not of individual virus particles. 

A New Mutant of Bacteriophage T2 

Two different classes of phage that give 
rise to mixed plaques have been described 
by Hershey and Chase. The first of these 
contains the heterozygotes, which have 
been extensively studied. A phage particle 
heterozygous with respect to the r (rapidly 
lysing) character, for example, yields equal 
numbers of r and r + progeny, and there- 
fore produces a visibly mottled plaque. 
Mixed plaques from the second type of un- 
stable particle are sectored rather than 
mottled. They contain unstable particles 
like the parent, and stable r particles, but 
no r + . An example of this second type of 
unstable particle has now been studied by 
Visconti and Symonds. Their results can 
be interpreted in terms of two genetic loci. 
One locus is the site of r mutations in the 
unstable particles; this locus is called R. 
The other locus is responsible for the sec- 
toring of the plaques, in a manner partly 
elucidated below; this locus is called u. 
The stock producing the sectored plaques 
is called R + u. 

Contrary to expectation, the rate of mu- 
tation of R^u to Ru is not excessive. As 
measured from the frequency of occur- 



DEPARTMENT OF GENETICS 



223 



rence in single bursts, it is about one in 10 4 
generations. Consistently with this normal 
rate, Ru mutants do not accumulate un- 
duly during the cultivation of R + u in 
broth. The sectoring of R + u plaques in 
agar is therefore due to conditions peculiar 
to the agar medium on the one hand, and 
to the presence in the phage of the u gene 
on the other. 

The R locus, that is, the R character in 
Ru mutants, is closely linked to the previ- 
ously known locus n, with a recombina- 
tion frequency of 0.3 per cent. Since sim- 
ilar mutants are not found in the wild- 



type stocks with appreciable frequency (n 
itself is unique), one function of the u 
locus is to cause the selection of a unique 
class of r mutants in agar. 

The loci R and u are themselves closely 
linked, with a recombination frequency of 
about 2 per cent. 

The sectoring of R^u plaques must be 
due to selection (in agar but not in broth) 
in favor of the Ru mutant. Whether this 
unique behavior should be attributed to 
the R or the u character has not been de- 
termined, and the precise role of the u 
locus remains to be investigated. 



ROLE OF DESOXYRIBOSE NUCLEIC ACID IN BACTERIOPHAGE 

INFECTION 

A. D. Hershey, June Dixon Hudis, and Martha Chase 



Our report last year summarized evi- 
dence that infection of Escherichia coli by 
phage T2 starts off with the injection of 
the viral nucleic acid into the cell, leaving 
most of the viral protein on the cell surface 
in metabolically inert form. This situation 
seemed to offer a unique opportunity to 
learn something about the function of nu- 
cleic acid in viral infection, and, more 
specifically, to inquire into the chemical 
basis of viral inheritance. At the outset it 
was clear that this project would call for 
a number of different lines of investigation 
into the chemistry of viral growth. During 
the current year we have made an appre- 
ciable start along two of these lines. 

The first question we have considered is 
whether any protein is injected into the 
cell along with the viral desoxyribose nu- 
cleic acid (DNA). This question calls for 
the use of isotopically labeled phage. We 
have prepared phage uniformly labeled by 
growth in a medium containing Cizf-glu- 
cose of high specific activity. Our experi- 
ments with this material have been explora- 
tory, and only provisional conclusions can 



be drawn from them. They were of three 
types : 

1. Ci4-labeled phage was allowed to at- 
tach to sensitive bacteria, and the suspen- 
sion was spun in a Waring Blendor for 2.5 
minutes, and then separated into cellular 
and extracellular fractions by centrifuga- 
tion. The infected cells remained compe- 
tent to yield phage. Both fractions were 
then analyzed for labeled amino acids, 
purines, and pyrimidines by paper chro- 
matography and radio assay. It was found 
that the cellular fraction contained 80 per 
cent of each of the purines and pyrimidines 
contained in the whole phage, but only 20 
per cent of each of several amino acids, in- 
cluding lysine and arginine. 

The proper interpretation of this result, 
which is in agreement with the earlier 
work with phage labeled with P32 and S35, 
is as follows. The phage particles attach to 
the bacteria by the ends of their tails. All 
or most of the nucleic acid of most of the 
particles then passes into the bacterial cells, 
presumably through the tails of the par- 
ticles. After this happens it is possible to 



224 



CARNEGIE INSTITUTION OF WASHINGTON 



strip the empty viral membranes from the is, the protein content of the complex is 
cells, by spinning in the Waring Blendor, appreciably less than 5 per cent by weight, 
without affecting the subsequent course of Additional experiments of the same type 
the infection. This treatment apparently with S35-labeled phage have shown that 
breaks the tails of the particles, leaving the membrane protein content of the super- 
stubs attached to the cells, as judged by the natant fluid can be reduced to about 0.5 per 
properties and microscopic appearance cent by repeated centrifugation at 30,000 g. 
(Levinthal) of the material stripped off. This suggests that the 5 per cent of protein 
The stubs of the tails presumably account analyzed above consisted of fragments of 
for the 20 per cent of protein, resembling membranes, and shows that more sensi- 
tive whole viral membranes in amino acid tive tests for basic protein will be feasible 
composition, left on the cells after strip- if this source of contamination is reduced, 
ping. It is evident, however, that this type The apparently very low basic protein 
of experiment cannot detect any protein content of resting particles of T2 might be 
differing in composition from the mem- interpreted as an extreme example of the 
branes and comprising appreciably less rule deduced by Mirsky and his collabora- 
than 20 per cent of the total viral protein, tors from analyses of chromosomes of dif- 
Nor can it reveal anything about the func- ferent types of cells, namely, that the con- 
tion of the protein not removed by strip- tent of basic protein is correlated with 
ping. different levels of metabolic activity of the 

2. In cells, and particularly in chromo- tissue of origin, 

somes of cells, desoxypentose nucleic acid 3. If all or part of the 20 per cent of viral 

is supposed to be associated with basic pro- protein that remains attached to infected 

teins rich in arginine or lysine. If this is cells after stripping in the Waring Blendor 

true of the nucleic acid of T2, it should be has any metabolic function in viral growth, 

possible to detect nonmembrane protein it might be expected that some of the 

after disrupting the phage particles by os- parental amino acids would be incorpo- 

motic shock. rated into the viral progeny, as is true of 

We subjected Ci4-labeled T2 to osmotic the constituents of the parental nucleic 

shock, and digested the nucleic acid with acid. Preliminary experiments by us, by 

the enzyme desoxyribonuclease. Most of Kozloff, and by French have failed to 

the membrane protein was then removed, demonstrate transfer of amino acids, but 

in one experiment by centrifugation at the best use has not yet been made of the 

30,000 g, in another experiment by precip- available techniques. 

itation with antiphage. In both experi- The analyses described above confirm, 

ments the supernatant fluids contained on the whole, the conjecture that viral 

about 5 per cent of the total viral protein, nucleic acid rules viral reproduction, and 

and the unprecipitated fraction did not dif- hence viral inheritance. At the same time 

fer in amino acid composition from the re- it is clear that static analysis will not lead 

mainder. The supernatant fluids also con- to any really decisive proof of this idea, 

tained nearly all the viral nucleic acid (in As a second approach, we have planned a 

degraded form), and one or both should comparative study of the times and rates 

have contained any protein originally asso- of synthesis of viral protein and nucleic 

ciated with the nucleic acid. We conclude acid during viral growth in infected cells, 

that the viral nucleic acid is not associated The analysis of protein and nucleic acid 

with a characteristic protein, or that, if it synthesis represents two major projects, 



DEPARTMENT OF GENETICS 



225 



which need to be co-ordinated not only 
with each other but also with related work 
already under way in other laboratories, 
particularly the immunological studies of 
viral growth being carried on by Luria and 
his collaborators. At the present time, only 
the work on nucleic acid synthesis has 
progressed very far. Accordingly, we shall 
summarize the results of this work without 
saying much about its bearing on the larger 
questions. 

The questions we have asked about nu- 
cleic acid synthesis are very simple. We 
know from Doermann's work that infec- 
tive phage particles begin to form in the 
infected cell about 10 minutes after infec- 
tion, and that some masked form of the 
virus has already multiplied to a consider- 
able extent before this time. We asked 
how much nucleic acid is formed during 
this period of blind multiplication, and 
whether such nucleic acid is in fact the 
nucleic acid of future virus particles. 

One method of attack depended on the 
fortunate circumstance that the nucleic 
acid of T2 contains 5-hydroxymethyl cyto- 
sine, whereas the desoxyribonucleic acid of 
the bacterial host contains only the usual 
purines and pyrimidines. Making use of 
these facts, we were able to work out a 
quantitative chromatographic method of 
analysis for the two kinds of nucleic acid 
in infected bacteria. By this method we 
found that the bacterial nucleic acid dis- 
appears during the first 25 minutes of 
viral growth, and that viral nucleic acid 
begins to accumulate promptly after in- 
fection. At 10 minutes, when infective 
virus is just beginning to reappear, the 
characteristic viral nucleic acid already 
measures about 50 units (phage-particle 
equivalents) per bacterium. After this 
time, the synthesis of nucleic acid keeps 
pace with the formation of infective par- 
ticles in such a way that the cell always 



contains 50 to 100 units of surplus nucleic 
acid. 

To determine whether this surplus nu- 
cleic acid is a precursor of the infective 
particles, as it should be if the hypothetical 
vegetative form of the virus contains nu- 
cleic acid, we made a rather thorough 
study of the kinetics of DNA synthesis and 
phage maturation, using P32 as a nucleic 
acid label. 

The experimental principles are outlined 
in figure 5, which divides the source of 




Sink 



Preassimilated , 
postassimilated, 
and parental 
phosphorus 

Fig. 5. Experimental arrangements for the 
analysis of precursor phosphorus. P' ', phage- 
precursor P32; P, phage-precursor phosphorus 
(P31+P32); V ', mature-phage P32; V, mature- 
phage phosphorus. (Reprinted from Journal of 
General Physiology, vol. 37, 1953, p. 2.) 

phosphorus for viral growth into three 
parts: phosphorus assimilated by the bac- 
teria before infection, which is first in- 
corporated into bacterial DNA (KozlofT) ; 
phosphorus contained in the parental 
phage; and phosphorus assimilated by the 
bacteria after infection. Any one of these 
three parts can be separately labeled with 
P32, as was shown previously by Cohen, 
and by Putnam and KozlofT. 

We first labeled phosphorus assimilated 
after infection, and particularly phosphorus 
assimilated during the first 4 minutes after 
infection. Atoms of this phosphorus were 
found to be incorporated into nucleic acid 
after spending an average of 8 or 9 min- 



226 



CARNEGIE INSTITUTION OF WASHINGTON 



utes in the cell. The radioactive phos- 
phorus in the newly synthesized nucleic 
acid was later incorporated almost com- 
pletely into infective phage particles. The 
second step in the transport required an 
additional 7 or 8 minutes. These times are 
in good agreement with the results of Stent 
and Maal0e, who found that the transport 
from medium to phage required about 14 
minutes. 

These results showed that one of the pre- 
cursors of the virus is nucleic acid synthe- 
sized after infection, presumably the sur- 
plus cytosineless nucleic acid previously 
detected by chromatographic analysis. 

We next inquired whether this surplus 
nucleic acid is the sole or principal imme- 
diate precursor of the nucleic acid of ma- 
ture virus. This is equivalent to saying 
that the precursor pool indicated in figure 
5 is a unitary pool, and contains only cyto- 
sineless nucleic acid. Moreover, if it con- 
tains all the cytosineless nucleic acid, as 
indicated by the completeness of the trans- 
fer of early-assimilated phosphorus, the 
size of the pool is known from measure- 
ments already described: it contains 50 to 
100 phage-particle equivalents of precursor 
nucleic acid. 

This prediction could be tested inde- 
pendently of the assumption that the pre- 
cursor is nucleic acid. We knew that the 
precursor is converted into phage by an 
irreversible process, because practically all 
the early-assimilated P32 eventually ends 
up in phage. Accordingly, we could define 
the specific radioactivity of phosphorus in 
the precursor pool (see fig. 5) by the rela- 
tion dV'/dV=P'/P. According to this re- 
lation, the specific activity of the precursor 
pool (P'/P) can be measured by measur- 
ing the specific activity (dV fdV) of a 
sample that has just been converted into 
mature phage. 

Suppose, now, that a small amount of 
P32 is admitted into the precursor pool at 



the very start, by infecting the cells with 
labeled phage. There is, to be sure, a com- 
plication arising from the fact that not all 
the parental phosphorus enters the pool; 
about 60 per cent of it goes into a "sink" of 
nonprecursor material. Taking this into 
account, we shall expect that when the first 
phage particles are formed they will receive 
nucleic acid drawn from a pool containing 
about 40 per cent of the parental radioac- 
tive nucleic acid, diluted by about 50 units 
per bacterium of newly synthesized, non- 
radioactive nucleic acid. Thus the first 
virus particle formed in a bacterium in- 
fected with P32-labeled phage should con- 
tain about 0.8 per cent as much P32 as was 
present in the parental particles. A slight 
extension of this reasoning permits a very 
precise measure of the size of the precursor 
pool by analysis of the kinetics of transfer 
of parental phosphorus to progeny phage. 

This analysis shows that the precursor 
pool contains phosphorus equivalent to 54 
to 94 phage particles per bacterium, in 
agreement with direct measures of the 
amount of nucleic acid synthesized after 
infection. We conclude, therefore, that the 
precursor pool contains all its phosphorus 
in the form of nucleic acid, and contains 
all the nucleic acid synthesized after infec- 
tion and not yet incorporated into infective 
particles. 

A similar analysis of the preassimilated 
bacterial phosphorus shows that it is not 
present in the pool of immediate viral- 
precursor nucleic acid, but enters this pool 
gradually during viral growth. This result 
agrees with the fact, since established by 
Kozloff, that the precursor material is bac- 
terial nucleic acid, and has to be converted 
into cytosineless nucleic acid before it is 
directly available for viral growth. We 
find that this conversion is completed in 
about 25 minutes. 

As a whole, the tracer experiments show 
that viral nucleic acid is synthesized at the 



DEPARTMENT OF GENETICS 



227 



rate to be expected if the precursor nucleic 
acid is contained in the vegetative phage 
particles identified by genetic methods. It 
remains to be seen whether the synthesis 
of viral-precursor protein obeys the same 
or different rules. 

Molecular Characteristics of the DNA 
Component of Phage T2 

In view of the primary role played by 
the viral desoxyribose nucleic acid (DNA) 
in the multiplication of phage T2, the mo- 
lecular characteristics of this material have 
been investigated by Garen in collabora- 
tion with Dr. E. Reichmann, of the Chem- 
istry Department of Harvard University. 
The DNA of T2 was separated from its 
protein membrane by several shakings of 



an aqueous suspension of the phage in the 
presence of chloroform. This procedure 
removes most of the sulfur-containing pro- 
tein (as indicated by the residual radioac- 
tivity when S35-labeled phage is used as 
a tracer) and recovers more than 50 per 
cent of the DNA. Preliminary measure- 
ments of the isolated DNA by light-scat- 
tering techniques indicate a molecular 
weight of ten million. From this value we 
can estimate that a mature particle of 
phage T2 contains around 10 molecules of 
DNA of this molecular weight. Further 
experiments are now in progress, using 
viscosity and rotary-diffusion techniques 
in addition to light scattering, to gain ad- 
ditional information about the size and 
shape of the molecules. 



MUTATION IN MAIZE 

Barbara McClintock 



The origin of instability at a number of 
loci of known genie action in maize chro- 
mosomes has been described in previous 
Year Books, and the nature of the unstable 
expression discussed. In some of these cases, 
instability appeared when Ds, a trans- 
posable chromosomal unit, was inserted 
next to the locus. The original and the 
subsequent mutations were shown to be 
expressions of changes induced at the locus 
by Ds. Ds is known to produce chromatin 
alterations. It was suspected, therefore, 
that the mutations it induces may be ac- 
companied by some form of chromatin al- 
teration or reorganization. If so, no two 
mutation-inducing events need produce ex- 
actly the same type of change at the locus, 
even though the resulting modification 
effects the same change in expression of 
the known genetic factor. It was decided, 
therefore, to examine a number of Ds- 
induced mutations in order to determine 
whether or not differences could be de- 



tected among them. For this purpose, a 
number of independently occurring muta- 
tions at a selected locus were required. 
The two cases, described in Year Book 
No. 51 (1951-1952), in which Ds was in- 
serted into the short arm of chromosome 
9 just to the left of Shi were selected 
because each has provided a large num- 
ber of newly induced mutations to shi 
(shrunken endosperm). 

Origin of the Mutants 

All the mutants used in this study ap- 
peared in the progeny derived from crosses 
of plants homozygous for C, ds, shi, and 
bz, and carrying no Ac factor, to plants 
having Ac and one of the following con- 
stitutions: (1) I Ds Shi Bz/I Ds Shi Bz, 
(2) IDs Shi Bz/I Ds Shi bz, or (3) / Ds 
Shi Bz/C ds shi bz. I (inhibitor of aleu- 
rone color, dominant in action to C, which 
produces aleurone color) is located approx- 
imately four crossover units to the left of 



228 



CARNEGIE INSTITUTION OF WASHINGTON 



Shi. Bz (allele of bz, recessive mutant 
which alters the color of the aleurone layer 
and the plant tissues to a bronze shade) is 
located approximately two crossover units 
to the right of Shi. 

The frequency of occurrence of germinal 
mutations to shi among the kernels on the 
ears resulting from the above-described 
crosses was recorded in Year Book No. 51. 
On the ears produced by the first two of 
these crosses, a few completely colored, Shi 
kernels were present. Such kernels were 
expected for the following reasons. In the 
two cases under consideration, most of the 
alterations produced by Ds result in a di- 
centric chromatid and a reciprocal acen- 
tric fragment. The position of break in the 
short arm of chromosome 9 is at the locus 
of Ds, just to the left of Sh±. The acentric 
fragment, carrying /, is subsequently lost 
during a mitotic cycle. If such an event 
occurs in a premeiotic, meiotic, or gameto- 
phytic nucleus, gametes may be formed 
that are deficient for a segment of chromo- 
some 9 extending from the locus of Ds to 
the end of the arm. Previous studies had 
shown that female gametophytes having 
such deficiencies are viable and functional, 
and that kernels in which / is absent can 
be produced from them. In the crosses de- 
scribed here, such kernels should be com- 
pletely colored. Plants derived from them 
should have a long terminal deficiency of 
the short arm of one of their chromosomes 
9. As will be shown later, this proved true 
of only some of these plants. Morphologi- 
cally normal chromosomes 9 were present 
in the others, but the action of / carried by 
the chromosome received from the female 
parent was inhibited. 

Change in Action of Genes Located 
to the Right of Ds 

An analysis of plants derived from some 
of the kernels carrying newly induced shi 



mutants that appeared on the ears from 
cross 3 listed above was given in Year 
Book No. 51. The mutants appearing on 
the ears from crosses 1 and 2, however, are 
of particular importance, because neither 
crossing over in a heterozygote nor con- 
tamination could account for the mutant 
phenotype. Forty-nine plants carrying 
newly induced alterations at the locus of 
Shi have been examined. All were derived 
from kernels that were I shi in phenotype. 
Sixteen were selected from the ears pro- 
duced by cross 1. Ten of these kernels 
were completely colorless, indicating the 
absence of either Ds or Ac. In four others, 
areas exhibiting either the C Bz or the 
C bz phenotype were present, indicating 
the presence of both Ds and Ac. In the 
remaining two kernels, areas showing only 
the C bz phenotype appeared, indicating 
the absence or inhibition of Bz. Nine I shi 
kernels were selected from the ears pro- 
duced by cross 2. Five of them were com- 
pletely colorless, and four had areas of 
both the C Bz and the C bz phenotypes. 
From the ears produced by cross 3, nine- 
teen / shi kernels were selected that 
showed areas of the C Bz and the C bz 
phenotypes, and five additional kernels 
were selected that showed areas only of 
the C bz phenotype. 

Subsequent study showed that in thirty- 
seven of the forty -nine plants derived from 
the selected I shi kernels, Bz was present 
in the / chromosome and unmodified in 
action. The remaining twelve plants were 
all bronze {bz) in phenotype. As will be 
shown later, this phenotype appeared in 
some of these plants because the locus of 
Bz had been altered by the same event that 
had altered the Shi locus. 

Comparisons between shi Mutants 

Modification affecting only Shi. Simi- 
larities and differences among the thirty- 



DEPARTMENT OF GENETICS 



229 



seven cases of mutation to shi in which 
the action of Bz was unaffected by the mu- 
tation-inducing event will be considered 
first. In all cases, the chromosome carrying 
the new shi mutation was transmitted nor- 
mally through the male and female game- 
tophytes, and the homozygotes were viable. 
Ds was present in each, and its position 
was not detectably altered by the event 
that produced the mutation to shi. Rever- 
sions to Shx occurred in nine of the thirty- 
seven cases. In two of them the frequency 
of reversion was high, and in both cases it 
was ^-controlled. The reversions to Shi 
were not associated with loss or change in 
location of Ds. The behavior of the shi 
mutants differed not only with regard to 
the occurrence of reversions, and to fre- 
quencies of reversions when they did occur, 
but also with regard to frequency of cross- 
ing over between the locus of shi and the 
loci of its nearest known neighbors, / and 
Bz. In one case consistent results have 
been obtained in tests extending over three 
successive generations. When this shi is 
present, crossing over between / and shi is 
increased about 50 per cent, in comparison 
with standard frequencies, and crossing 
over between shi and Bz is increased ap- 
proximately 300 per cent. In several other 
cases, the mutation to shi resulted in 
marked reductions in crossing over. In a 
backcross test involving one such case, no 
crossing over between shi and Bz was ob- 
served in a total of 3156 tested gametes; 
crossing over between / and shi was 
slightly reduced, but that between Bz and 
a marker, Wx, located to the right of Bz, 
was unaltered. In all cases where a modi- 
fication in crossing over was expressed, it 
was confined to the vicinity of the shi 
locus. 

It may be concluded that the described 
dissimilarities among these shi mutants 
reflected dissimilarities in the primary mu- 



tation-inducing events, even though all 
were initiated by Ds. 

Simultaneous modification of the action 
of Shi and its neighboring gene, Bz. As 
was stated above, twelve of the forty-nine 
plants derived from / shi kernels produced 
from crosses 1 to 3 exhibited the reces- 
sive bronze phenotype. Four of the ker- 
nels from which these plants arose had 
appeared on ears produced by cross 1, three 
came from ears produced by cross 2, and 
five from ears produced by cross 3. (These 
last five were selected because of the ap- 
pearance of C bz areas in the aleurone 
layer and the complete absence of any de- 
tectable Bz action, and also because in four 
of them the endosperm was noticeably de- 
fective.) Only in the four cases derived 
from cross 1 was it certain that the Shi 
and Bz loci had been altered by the same 
event. The female parent in this cross was 
homozygous for both Shi and Bz; whereas 
one of the chromosomes 9 in the female 
parents used in the other two crosses car- 
ried the known recessive, bz. In the re- 
maining eight of the twelve plants, the 
presence of this recessive in the / .^-car- 
rying chromosome could account for the 
bronze phenotypic expression, the mu- 
tation-inducing event having altered only 
the Shi locus. Evidence obtained from 
subsequent study of one of the three cases 
derived from cross 2 and four of the five 
cases derived from cross 3 suggests, how- 
ever, that a longer segment within the 
chromosome had been altered, and that it 
extended from the locus of Ds to or be- 
yond that of Bz or its allele bz. This evi- 
dence will appear in the following dis- 
cussion. 

One of the four bronze plants obtained 
from the / shi kernels of cross 1 was com- 
pletely male- and female-sterile, and there- 
fore the modification responsible for the 
bronze phenotype could not be examined 
further. Cytological examination of the 



230 



CARNEGIE INSTITUTION OF WASHINGTON 



other three plants revealed no structural 
alteration in their chromosomes 9. Marked 
differences were noted, however, in genetic 
behavior. In one of them, the /-carrying 
chromosome behaved as though the known 
recessives, shi and bz, were present, in that 
it was normally transmitted through the 
male and female gametophytes, and the 
kernels homozygous for it were normal in 
appearance. Also, no reversions to Shi or 
Bz were observed. The behavior of the 
/-carrying chromosome in the other two 
plants was decidedly aberrant. It suggested 
that a segment of the chromosome, includ- 
ing the Shi and Bz loci, was either absent 
or greatly modified. In one of these cases, 
transmission of the chromosome was nearly 
normal through the female gametophyte 
but markedly reduced through the pollen 
grain. Kernels homozygous for the modi- 
fied segment were not produced, and most 
of the kernels heterozygous for it were ab- 
normal in appearance — smaller than nor- 
mal and showing few to many wrinkled 
regions. In the second of these two cases, 
the chromosome was transmitted at a re- 
duced rate through the female gameto- 
phyte and was not transmitted through the 
pollen. Most of the kernels heterozygous 
for this segment were defective, and in 
many of them the embryo appeared to be 
dead. In both cases, Ds was present in the 
chromosome having the modified segment. 
Although its exact position has not yet 
been determined, in both cases it was 
either adjacent to or a component of the 
genetically modified segment. No rever- 
sions to Shi or to Bz were found in either 



case. 



The genetic behavior of the /-carrying 
chromosome in two of the three bronze 
plants grown from the / shi kernels from 
cross 2 was normal. It resembled that of 
a chromosome carrying the known reces- 
sives shi and bz. Ds was present in the 
chromosome in each of these plants, and 



not noticeably altered in location. The 
behavior of the / chromosome in the third 
plant was similar, except that somatic re- 
versions to Bz occurred and they were 
^-controlled. The frequency of reversion 
was low, and no germinal mutations ap- 
peared in tests of several thousand gametes. 
No reversions to Shi were observed. In 
the event that they did occur, with as low 
a frequency as the Bz reversions, detection 
would be difficult. Only germinal rever- 
sions to Shi, or those occurring in very 
early development of the kernel, can be 
recognized with certainty. Ds was present 
in this chromosome, and again its location 
had not been altered noticeably by the 
event that produced the changed pheno- 
typic expressions of Shi and Bz. It was 
close to shi and to the left of the mutable 
bz locus. 

In one of the five bronze plants derived 
from I shi kernels produced by cross 3, no 
aberrant behavior of the /-carrying chro- 
mosome was observed. Normal transmis- 
sion occurred through the male and female 
gametophytes, and the kernels heterozy- 
gous and homozygous for the chromosome 
were normal in appearance. Ds was pres- 
ent in this chromosome. No reversions to 
either Shi or Bz were seen. In the four 
remaining plants, the / chromosome be- 
haved as if it had a modified segment, the 
modification being similar to that in the 
two cases described above. Here, again, 
there was a reduction of gametophytic 
transmission of the chromosome carrying 
the modified segment. In one plant, trans- 
mission through the female gametophyte 
was normal, and that through the pollen 
grain only slightly reduced. The hetero- 
zygous kernels were normal in appear- 
ance, but no homozygotes were obtained. 
Another plant showed nearly normal 
transmission through the female gameto- 
phyte, but markedly reduced transmission 
through the pollen grain. No homozy- 



DEPARTMENT OF GENETICS 



23 1 



gous kernels were obtained, but the hetero- 
zygotes were normal in appearance. The 
behavior in the remaining two plants was 
similar to that in the plant just described, 
except that most of the kernels heterozy- 
gous for the modified segment were de- 
fective — small kernels, with few to many 
wrinkled areas. Cytological examination 
did not reveal a detectable structural modi- 
fication in the short arm of chromosome 9 
in any of the plants that were heterozygous 
for these modified segments. Again, Ds 
was present in all the chromosomes with 
modified segments, and it appeared to be 
located adjacent to or to be a component 
of the modified segment. No somatic re- 
version to either Shi or Bz was observed. 
Although it is clear from the descriptions 
above that alterations affecting both the 
locus of Shi and that of Bz had occurred 
in at least nine of these twelve cases, and 
that homozygotes exhibiting the recessive 
expression could be obtained from two of 
them, it is not yet possible to state whether 
or not deficiency was responsible for the 
recessive expression, except in the one case 
where reversion to Bz occurred. In that 
case, deficiency of Bz is excluded. Marked 
deleterious effects are produced by some of 
these alterations, even in the heterozygote; 
and this situation has not previously been 
encountered in studies of heterozygous de- 
ficiencies in maize. Although deficiency 
cannot be excluded as the cause of the re- 
cessive phenotypic expression in every case, 
there is at present no direct evidence of it 
in any one case. 

Change in Action of Genes Located to 
the Left of Ds 

The previous sections have considered 
changes in expression of known genes lo- 
cated to the right of Ds, namely, Shi and 
Bz. Changes in action of /, located four 
crossover units to the left of Ds, may also 



occur. Evidence of this has been obtained 
from plants derived from the colored ker- 
nels appearing on the ears of crosses 1 and 
2. As was explained earlier, the appear- 
ance of such colored kernels on these ears 
was anticipated; and plants derived from 
them were expected to have a chromosome 
9 with a long terminal deficiency of the 
short arm, extending from the locus of Ds 
to the end of the arm. It was considered 
necessary to test this expectation. Conse- 
quently, some of the colored kernels were 
selected and plants were grown from 
them. Eighteen plants were obtained from 
the colored kernels of cross 1 and two from 
those of cross 2. Owing to the pressure of 
other work, time was not found to ex- 
amine the chromosomes of these plants. 
In order to obtain seed for later examina- 
tion, each plant was self-pollinated and 
also crossed by plants homozygous for C, 
shi, and bz. The types of kernels appear- 
ing on the ears of three of the plants de- 
rived from colored kernels produced by 
cross 1 and one of the two plants derived 
from such kernels from cross 2 were quite 
unexpected. They indicated that the ap- 
pearance of color in the original kernel 
from which each plant arose was not due 
to a terminal deficiency, but rather to some 
more localized modification within chro- 
mosome 9 that had affected the action of /. 
Since the kernel types and the frequencies 
of types were the same on the ears of all 
four plants, they can be considered collec- 
tively. On the self-pollinated ears, a few 
completely colorless, Shi kernels appeared. 
There were 87 of them among a total of 
1224 kernels, and the percentages on the 
four ears were 4.6, 7.7, 7.7, and 9.0. The 
remaining kernels were all colored: 604 
were Shi, and nearly all of these were very 
lightly colored; 533 were shi, and these had 
the depth of color that is produced by three 
doses of C. On the ears resulting from 
the backcross, no colorless kernels were 



232 



CARNEGIE INSTITUTION OF WASHINGTON 



present. The Shi and shi classes of kernels 
appeared in equal frequencies. Nearly all 
the Shi kernels were lightly colored, and 
nearly all the shi